Part 2 out of 5
Axiom II.-When a body in motion impinges on another body at
rest, which it is unable to move, it recoils, in order to
continue its motion, and the angle made by the line of motion in
the recoil and the plane of the body at rest, whereon the moving
body has impinged, will be equal to the angle formed by the line
of motion of incidence and the same plane.
So far we have been speaking only of the most simple bodies,
which are only distinguished one from the other by motion and
rest, quickness and slowness. We now pass on to compound bodies.
Definition.-When any given bodies of the same or different
magnitude are compelled by other bodies to remain in contact, or
if they be moved at the same or different rates of speed, so that
their mutual movements should preserve among themselves a certain
fixed relation, we say that such bodies are in union, and that
together they compose one body or individual, which is
distinguished from other bodies by the fact of this union.
Axiom III.-In proportion as the parts of an individual, or a
compound body, are in contact over a greater or less superficies,
they will with greater or less difficulty admit of being moved
from their position ; consequently the individual will, with
greater or less difficulty, be brought to assume another form.
Those bodies, whose parts are in contact over large superficies,
are called hard ; those, whose parts are in contact over small
superficies, are called soft ; those, whose parts are in motion
among one another, are called fluid.
LEMMA IV. If from a body or individual, compounded of
several bodies, certain bodies be separated, and if, at the same
time, an equal number of other bodies of the same nature take
their place, the individual will preserve its nature as before,
without any change in its actuality (forma).
Proof.-Bodies (Lemma i.) are not distinguished in respect of
substance : that which constitutes the actuality (formam) of an
individual consists (by the last Def.) in a union of bodies ; but
this union, although there is a continual change of bodies, will
(by our hypothesis) be maintained ; the individual, therefore,
will retain its nature as before, both in respect of substance
and in respect of mode. Q.E.D.
LEMMA V. If the parts composing an individual become greater
or less, but in such proportion, that they all preserve the same
mutual relations of motion and rest, the individual will still
preserve its original nature, and its actuality will not be
Proof.-The same as for the last Lemma.
LEMMA VI. If certain bodies composing an individual be
compelled to change the motion, which they have in one direction,
for motion in another direction, but in such a manner, that they
be able to continue their motions and their mutual communication
in the same relations as before, the individual will retain its
own nature without any change of its actuality.
Proof.-This proposition is self-evident, for the individual
is supposed to retain all that, which, in its definition, we
spoke of as its actual being.
LEMMA VII. Furthermore, the individual thus composed
preserves its nature, whether it be, as a whole, in motion or at
rest, whether it be moved in this or that direction ; so long as
each part retains its motion, and preserves its communication
with other parts as before.
Proof.-This proposition is evident from the definition of an
individual prefixed to Lemma iv.
Note.-We thus see, how a composite individual may be affected
in many different ways, and preserve its nature notwithstanding.
Thus far we have conceived an individual as composed of bodies
only distinguished one from the other in respect of motion and
rest, speed and slowness ; that is, of bodies of the most simple
character. If, however, we now conceive another individual
composed of several individuals of diverse natures, we shall find
that the number of ways in which it can be affected, without
losing its nature, will be greatly multiplied. Each of its parts
would consist of several bodies, and therefore (by Lemma vi.)
each part would admit, without change to its nature, of quicker
or slower motion, and would consequently be able to transmit its
motions more quickly or more slowly to the remaining parts. If
we further conceive a third kind of individuals composed of
individuals of this second kind, we shall find that they may be
affected in a still greater number of ways without changing their
actuality. We may easily proceed thus to infinity, and conceive
the whole of nature as one individual, whose parts, that is, all
bodies, vary in infinite ways, without any change in the
individual as a whole. I should feel bound to explain and
demonstrate this point at more length, if I were writing a
special treatise on body. But I have already said that such is
not my object ; I have only touched on the question, because it
enables me to prove easily that which I have in view.
I. The human body is composed of a number of individual
parts, of diverse nature, each one of which is in itself
II. Of the individual parts composing the human body some
are fluid, some soft, some hard.
III. The individual parts composing the human body, and
consequently the human body itself, are affected in a variety of
ways by external bodies.
IV. The human body stands in need for its preservation of a
number of other bodies, by which it is continually, so to speak,
V. When the fluid part of the human body is determined by an
external body to impinge often on another soft part, it changes
the surface of the latter, and, as it were, leaves the impression
thereupon of the external body which impels it.
VI. The human body can move external bodies, and arrange
them in a variety of ways.
PROP. XIV. The human mind is capable of perceiving a great
number of things, and is so in proportion as its body is capable
of receiving a great number of impressions.
Proof.-The human body (by Post. iii. and vi.) is affected in
very many ways by external bodies, and is capable in very many
ways of affecting external bodies. But (II. xii.) the human
mind must perceive all that takes place in the human body ; the
human mind is, therefore, capable of perceiving a great number of
things, and is so in proportion, &c. Q.E.D.
PROP. XV. The idea, which constitutes the actual being of the
human mind, is not simple, but compounded of a great number of
Proof.-The idea constituting the actual being of the human
mind is the idea of the body (II. xiii.), which (Post. i.) is
composed of a great number of complex individual parts. But
there is necessarily in God the idea of each individual part
whereof the body is composed (II. viii. Coroll.) ; therefore
(II. vii.), the idea of the human body is composed of these
numerous ideas of its component parts. Q.E.D.
PROP. XVI. The idea of every mode, in which the human body is
affected by external bodies, must involve the nature of the human
body, and also the nature of the external body.
Proof.-All the modes, in which any given body is affected,
follow from the nature of the body affected, and also from the
nature of the affecting body (by Ax. i., after the Coroll. of
Lemma iii.), wherefore their idea also necessarily (by I. Ax.
iv.) involves the nature of both bodies ; therefore, the idea of
every mode, in which the human body is affected by external
bodies, involves the nature of the human body and of the external
Corollary I.-Hence it follows, first, that the human mind
perceives the nature of a variety of bodies, together with the
nature of its own.
Corollary II.-It follows, secondly, that the ideas, which we
have of external bodies, indicate rather the constitution of our
own body than the nature of external bodies. I have amply
illustrated this in the Appendix to Part I.
PROP. XVII. If the human body is affected in a manner which
involves the nature of any external body, the human mind will
regard the said external body as actually existing, or as present
to itself, until the human body be affected in such a way, as to
exclude the existence or the presence of the said external body.
Proof.-This proposition is self-evident, for so long as the
human body continues to be thus affected, so long will the human
mind (II. xii.) regard this modification of the body-that is (by
the last Prop.), it will have the idea of the mode as actually
existing, and this idea involves the nature of the external body.
In other words, it will have the idea which does not exclude, but
postulates the existence or presence of the nature of the
external body ; therefore the mind (by II. xvi., Coroll. i.) will
regard the external body as actually existing, until it is
affected, &c. Q.E.D.
Corollary.-The mind is able to regard as present external
bodies, by which the human body has once been affected, even
though they be no longer in existence or present.
Proof.-When external bodies determine the fluid parts of the
human body, so that they often impinge on the softer parts, they
change the surface of the last named (Post. v.) ; hence (Ax. ii.,
after the Coroll. of Lemma iii.) they are refracted therefrom in
a different manner from that which they followed before such
change ; and, further, when afterwards they impinge on the new
surfaces by their own spontaneous movement, they will be
refracted in the same manner, as though they had been impelled
towards those surfaces by external bodies ; consequently, they
will, while they continue to be thus refracted, affect the human
body in the same manner, whereof the mind (II. xii.) will again
take cognizance-that is (II. xvii.), the mind will again regard
the external body as present, and will do so, as often as the
fluid parts of the human body impinge on the aforesaid surfaces
by their own spontaneous motion. Wherefore, although the
external bodies, by which the human body has once been affected,
be no longer in existence, the mind will nevertheless regard them
as present, as often as this action of the body is repeated.
Note.-We thus see how it comes about, as is often the case,
that we regard as present many things which are not. It is
possible that the same result may be brought about by other
causes ; but I think it suffices for me here to have indicated
one possible explanation, just as well as if I had pointed out
the true cause. Indeed, I do not think I am very far from the
truth, for all my assumptions are based on postulates, which
rest, almost without exception, on experience, that cannot be
controverted by those who have shown, as we have, that the human
body, as we feel it, exists (Coroll. after II. xiii.).
Furthermore (II. vii. Coroll., II. xvi. Coroll. ii.), we clearly
understand what is the difference between the idea, say, of
Peter, which constitutes the essence of Peter's mind, and the
idea of the said Peter, which is in another man, say, Paul. The
former directly answers to the essence of Peter's own body, and
only implies existence so long as Peter exists ; the latter
indicates rather the disposition of Paul's body than the nature
of Peter, and, therefore, while this disposition of Paul's body
lasts, Paul's mind will regard Peter as present to itself, even
though he no longer exists. Further, to retain the usual
phraseology, the modifications of the human body, of which the
ideas represent external bodies as present to us, we will call
the images of things, though they do not recall the figure of
things. When the mind regards bodies in this fashion, we say
that it imagines. I will here draw attention to the fact, in
order to indicate where error lies, that the imaginations of the
mind, looked at in themselves, do not contain error. The mind
does not err in the mere act of imagining, but only in so far as
it is regarded as being without the idea, which excludes the
existence of such things as it imagines to be present to it. If
the mind, while imagining non-existent things as present to it,
is at the same time conscious that they do not really exist, this
power of imagination must be set down to the efficacy of its
nature, and not to a fault, especially if this faculty of
imagination depend solely on its own nature-that is (I. Def.
vii.), if this faculty of imagination be free.
PROP. XVIII. If the human body has once been affected by two or
more bodies at the same time, when the mind afterwards imagines
any of them, it will straightway remember the others also.
Proof.-The mind (II. xvii. Coroll.) imagines any given body,
because the human body is affected and disposed by the
impressions from an external body, in the same manner as it is
affected when certain of its parts are acted on by the said
external body ; but (by our hypothesis) the body was then so
disposed, that the mind imagined two bodies at once ; therefore,
it will also in the second case imagine two bodies at once, and
the mind, when it imagines one, will straightway remember the
Note.-We now clearly see what Memory is. It is simply a
certain association of ideas involving the nature of things
outside the human body, which association arises in the mind
according to the order and association of the modifications
(affectiones) of the human body. I say, first, it is an
association of those ideas only, which involve the nature of
things outside the human body : not of ideas which answer to the
nature of the said things : ideas of the modifications of the
human body are, strictly speaking (II. xvi.), those which involve
the nature both of the human body and of external bodies. I say,
secondly, that this association arises according to the order and
association of the modifications of the human body, in order to
distinguish it from that association of ideas, which arises from
the order of the intellect, whereby the mind perceives things
through their primary causes, and which is in all men the same.
And hence we can further clearly understand, why the mind from
the thought of one thing, should straightway arrive at the
thought of another thing, which has no similarity with the first
; for instance, from the thought of the word pomum (an apple), a
Roman would straightway arrive at the thought of the fruit apple,
which has no similitude with the articulate sound in question,
nor anything in common with it, except that the body of the man
has often been affected by these two things ; that is, that the
man has often heard the word pomum, while he was looking at the
fruit ; similarly every man will go on from one thought to
another, according as his habit has ordered the images of things
in his body. For a soldier, for instance, when he sees the
tracks of a horse in sand, will at once pass from the thought of
a horse to the thought of a horseman, and thence to the thought
of war, &c. ; while a countryman will proceed from the thought of
a horse to the thought of a plough, a field, &c. Thus every man
will follow this or that train of thought, according as he has
been in the habit of conjoining and associating the mental images
of things in this or that manner.
PROP. XIX. The human mind has no knowledge of the body, and does
not know it to exist, save through the ideas of the modifications
whereby the body is affected.
Proof.-The human mind is the very idea or knowledge of the
human body (II. xiii.), which (II. ix.) is in God, in so far as
he is regarded as affected by another idea of a particular thing
actually existing : or, inasmuch as (Post. iv.) the human body
stands in need of very many bodies whereby it is, as it were,
continually regenerated ; and the order and connection of ideas
is the same as the order and connection of causes (II. vii.) ;
this idea will therefore be in God, in so far as he is regarded
as affected by the ideas of very many particular things. Thus
God has the idea of the human body, or knows the human body, in
so far as he is affected by very many other ideas, and not in so
far as he constitutes the nature of the human mind ; that is (by
II. xi. Coroll.), the human mind does not know the human body.
But the ideas of the modifications of body are in God, in so far
as he constitutes the nature of the human mind, or the human
mind perceives those modifications (II. xii.), and consequently
(II. xvi.) the human body itself, and as actually existing ;
therefore the mind perceives thus far only the human body.
PROP. XX. The idea or knowledge of the human mind is also in
God, following in God in the same manner, and being referred to
God in the same manner, as the idea or knowledge of the human
Proof.-Thought is an attribute of God (II. i.) ; therefore
(II. iii.) there must necessarily be in God the idea both of
thought itself and of all its modifications, consequently also of
the human mind (II. xi.). Further, this idea or knowledge of the
mind does not follow from God, in so far as he is infinite, but
in so far as he is affected by another idea of an individual
thing (II. ix.). But (II. vii.) the order and connection of
ideas is the same as the order and connection of causes ;
therefore this idea or knowledge of the mind is in God and is
referred to God, in the same manner as the idea or knowledge of
the body. Q.E.D.
PROP. XXI. This idea of the mind is united to the mind in the
same way as the mind is united to the body.
Proof.-That the mind is united to the body we have shown from
the fact, that the body is the object of the mind (II. xii. and
xiii.) ; and so for the same reason the idea of the mind must be
united with its object, that is, with the mind in the same manner
as the mind is united to the body. Q.E.D.
Note.-This proposition is comprehended much more clearly from
what we have said in the note to II. vii. We there showed that
the idea of body and body, that is, mind and body (II. xiii.),
are one and the same individual conceived now under the attribute
of thought, now under the attribute of extension ; wherefore the
idea of the mind and the mind itself are one and the same thing,
which is conceived under one and the same attribute, namely,
thought. The idea of the mind, I repeat, and the mind itself are
in God by the same necessity and follow from him from the same
power of thinking. Strictly speaking, the idea of the mind, that
is, the idea of an idea, is nothing but the distinctive quality
(forma) of the idea in so far as it is conceived as a mode of
thought without reference to the object ; if a man knows
anything, he, by that very fact, knows that he knows it, and at
the same time knows that he knows that he knows it, and so on to
infinity. But I will treat of this hereafter.
PROP. XXII. The human mind perceives not only the modifications
of the body, but also the ideas of such modifications.
Proof.-The ideas of the ideas of modifications follow in God
in the same manner, and are referred to God in the same manner,
as the ideas of the said modifications. This is proved in the
same way as II. xx. But the ideas of the modifications of the
body are in the human mind (II. xii.), that is, in God, in so far
as he constitutes the essence of the human mind ; therefore the
ideas of these ideas will be in God, in so far as he has the
knowledge or idea of the human mind, that is (II. xxi.), they
will be in the human mind itself, which therefore perceives not
only the modifications of the body, but also the ideas of such
PROP. XXIII. The mind does not know itself, except in so far as
it perceives the ideas of the modifications of the body.
Proof.-The idea or knowledge of the mind (II. xx.) follows in
God in the same manner, and is referred to God in the same
manner, as the idea or knowledge of the body. But since (II.
xix.) the human mind does not know the human body itself, that is
(II. xi. Coroll.), since the knowledge of the human body is not
referred to God, in so far as he constitutes the nature of the
human mind ; therefore, neither is the knowledge of the mind
referred to God, in so far as he constitutes the essence of the
human mind ; therefore (by the same Coroll. II. xi.), the human
mind thus far has no knowledge of itself. Further the ideas of
the modifications, whereby the body is affected, involve the
nature of the human body itself (II. xvi.), that is (II. xiii.),
they agree with the nature of the mind ; wherefore the knowledge
of these ideas necessarily involves knowledge of the mind ; but
(by the last Prop.) the knowledge of these ideas is in the human
mind itself ; wherefore the human mind thus far only has
knowledge of itself. Q.E.D.
PROP. XXIV. The human mind does not involve an adequate
knowledge of the parts composing the human body.
Proof.-The parts composing the human body do not belong to
the essence of that body, except in so far as they communicate
their motions to one another in a certain fixed relation (Def.
after Lemma iii.), not in so far as they can be regarded as
individuals without relation to the human body. The parts of the
human body are highly complex individuals (Post. i.), whose
parts (Lemma iv.) can be separated from the human body without in
any way destroying the nature and distinctive quality of the
latter, and they can communicate their motions (Ax. i., after
Lemma iii.) to other bodies in another relation ; therefore (II.
iii.) the idea or knowledge of each part will be in God,
inasmuch (II. ix.) as he is regarded as affected by another idea
of a particular thing, which particular thing is prior in the
order of nature to the aforesaid part (II. vii.). We may affirm
the same thing of each part of each individual composing the
human body ; therefore, the knowledge of each part composing the
human body is in God, in so far as he is affected by very many
ideas of things, and not in so far as he has the idea of the
human body only, in other words, the idea which constitutes the
nature of the human mind (II. xiii) ; therefore (II. xi.
Coroll.), the human mind does not involve an adequate knowledge
of the human body. Q.E.D.
PROP. XXV. The idea of each modification of the human body does
not involve an adequate knowledge of the external body.
Proof.-We have shown that the idea of a modification of the
human body involves the nature of an external body, in so far as
that external body conditions the human body in a given manner.
But, in so far as the external body is an individual, which has
no reference to the human body, the knowledge or idea thereof is
in God (II. ix.), in so far as God is regarded as affected by the
idea of a further thing, which (II. vii.) is naturally prior to
the said external body. Wherefore an adequate knowledge of the
external body is not in God, in so far as he has the idea of the
modification of the human body ; in other words, the idea of the
modification of the human body does not involve an adequate
knowledge of the external body. Q.E.D.
PROP. XXVI. The human mind does not perceive any external body
as actually existing, except through the ideas of the
modifications of its own body.
Proof.-If the human body is in no way affected by a given
external body, then (II. vii.) neither is the idea of the human
body, in other words, the human mind, affected in any way by the
idea of the existence of the said external body, nor does it in
any manner perceive its existence. But, in so far as the human
body is affected in any way by a given external body, thus far
(II. xvi. and Coroll.) it perceives that external body. Q.E.D.
Corollary.-In so far as the human mind imagines an external
body, it has not an adequate knowledge thereof.
Proof.-When the human mind regards external bodies through
the ideas of the modifications of its own body, we say that it
imagines (see II. xvii. note) ; now the mind can only imagine
external bodies as actually existing. Therefore (by II. xxv.),
in so far as the mind imagines external bodies, it has not an
adequate knowledge of them. Q.E.D.
PROP. XXVII. The idea of each modification of the human body
does not involve an adequate knowledge of the human body itself.
Proof.-Every idea of a modification of the human body
involves the nature of the human body, in so far as the human
body is regarded as affected in a given manner (II. xvi.). But,
inasmuch as the human body is an individual which may be affected
in many other ways, the idea of the said modification, &c.
PROP. XXVIII. The ideas of the modifications of the human body,
in so far as they have reference only to the human mind, are not
clear and distinct, but confused.
Proof.-The ideas of the modifications of the human body
involve the nature both of the human body and of external bodies
(II. xvi.) ; they must involve the nature not only of the human
body but also of its parts ; for the modifications are modes
(Post. iii.), whereby the parts of the human body, and,
consequently, the human body as a whole are affected. But (by
II. xxiv., xxv.) the adequate knowledge of external bodies, as
also of the parts composing the human body, is not in God, in so
far as he is regarded as affected by the human mind, but in so
far as he is regarded as affected by other ideas. These ideas of
modifications, in so far as they are referred to the human mind
alone, are as consequences without premisses, in other words,
confused ideas. Q.E.D.
Note.-The idea which constitutes the nature of the human mind
is, in the same manner, proved not to be, when considered in
itself alone, clear and distinct ; as also is the case with the
idea of the human mind, and the ideas of the ideas of the
modifications of the human body, in so far as they are referred
to the mind only, as everyone may easily see.
PROP. XXIX. The idea of the idea of each modification of the
human body does not involve an adequate knowledge of the human
Proof.-The idea of a modification of the human body (II.
xxvii.) does not involve an adequate knowledge of the said body,
in other words, does not adequately express its nature ; that is
(II. xiii.) it does not agree with the nature of the mind
adequately ; therefore (I. Ax. vi) the idea of this idea does not
adequately express the nature of the human mind, or does not
involve an adequate knowledge thereof.
Corollary.-Hence it follows that the human mind, when it
perceives things after the common order of nature, has not an
adequate but only a confused and fragmentary knowledge of itself,
of its own body, and of external bodies. For the mind does not
know itself, except in so far as it perceives the ideas of the
modifications of body (II. xxiii.). It only perceives its own
body (II. xix.) through the ideas of the modifications, and only
perceives external bodies through the same means ; thus, in so
far as it has such ideas of modification, it has not an adequate
knowledge of itself (II. xxix.), nor of its own body (II.
xxvii.), nor of external bodies (II. xxv.), but only a
fragmentary and confused knowledge thereof (II. xxviii. and
Note.-I say expressly, that the mind has not an adequate but
only a confused knowledge of itself, its own body, and of
external bodies, whenever it perceives things after the common
order of nature ; that is, whenever it is determined from
without, namely, by the fortuitous play of circumstance, to
regard this or that ; not at such times as it is determined from
within, that is, by the fact of regarding several things at once,
to understand their points of agreement, difference, and
contrast. Whenever it is determined in anywise from within, it
regards things clearly and distinctly, as I will show below.
PROP. XXX. We can only have a very inadequate knowledge of the
duration of our body.
Proof.-The duration of our body does not depend on its
essence (II. Ax. i.), nor on the absolute nature of God (I.
xxi.). But (I. xxviii.) it is conditioned to exist and operate
by causes, which in their turn are conditioned to exist and
operate in a fixed and definite relation by other causes, these
last again being conditioned by others, and so on to infinity.
The duration of our body therefore depends on the common order of
nature, or the constitution of things. Now, however a thing may
be constituted, the adequate knowledge of that thing is in God,
in so far as he has the ideas of all things, and not in so far as
he has the idea of the human body only. (II. ix. Coroll.)
Wherefore the knowledge of the duration of our body is in God
very inadequate, in so far as he is only regarded as constituting
the nature of the human mind ; that is (II. xi. Coroll.), this
knowledge is very inadequate to our mind. Q.E.D.
PROP. XXXI. We can only have a very inadequate knowledge of the
duration of particular things external to ourselves.
Proof.-Every particular thing, like the human body, must be
conditioned by another particular thing to exist and operate in a
fixed and definite relation ; this other particular thing must
likewise be conditioned by a third, and so on to infinity. (I.
xxviii.) As we have shown in the foregoing proposition, from
this common property of particular things, we have only a very
inadequate knowledge of the duration of our body ; we must draw a
similar conclusion with regard to the duration of particular
things, namely, that we can only have a very inadequate knowledge
of the duration thereof. Q.E.D.
Corollary.-Hence it follows that all particular things are
contingent and perishable. For we can have no adequate idea of
their duration (by the last Prop.), and this is what we must
understand by the contingency and perishableness of things. (I.
xxxiii., Note i.) For (I. xxix.), except in this sense, nothing
PROP. XXXII. All ideas, in so far as they are referred to God,
Proof.-All ideas which are in God agree in every respect with
their objects (II. vii. Coroll.), therefore (I. Ax. vi.) they are
all true. Q.E.D.
PROP. XXXIII. There is nothing positive in ideas, which causes
them to be called false.
Proof.-If this be denied, conceive, if possible, a positive
mode of thinking, which should constitute the distinctive quality
of falsehood. Such a mode of thinking cannot be in God (II.
xxxii.) ; external to God it cannot be or be conceived (I. xv.).
Therefore there is nothing positive in ideas which causes them to
be called false. Q.E.D.
PROP. XXXIV. Every idea, which in us is absolute or adequate and
perfect, is true.
Proof.-When we say that an idea in us is adequate and
perfect, we say, in other words (II. xi. Coroll.), that the idea
is adequate and perfect in God, in so far as he constitutes the
essence of our mind ; consequently (II. xxxii.), we say that such
an idea is true. Q.E.D.
PROP. XXXV. Falsity consists in the privation of knowledge,
which inadequate, fragmentary, or confused ideas involve.
Proof.-There is nothing positive in ideas, which causes them
to be called false (II. xxxiii.) ; but falsity cannot consist in
simple privation (for minds, not bodies, are said to err and to
be mistaken), neither can it consist in absolute ignorance, for
ignorance and error are not identical ; wherefore it consists in
the privation of knowledge, which inadequate, fragmentary, or
confused ideas involve. Q.E.D.
Note.-In the note to II. xvii. I explained how error consists
in the privation of knowledge, but in order to throw more light
on the subject I will give an example. For instance, men are
mistaken in thinking themselves free ; their opinion is made up
of consciousness of their own actions, and ignorance of the
causes by which they are conditioned. Their idea of freedom,
therefore, is simply their ignorance of any cause for their
actions. As for their saying that human actions depend on the
will, this is a mere phrase without any idea to correspond
thereto. What the will is, and how it moves the body, they none
of them know ; those who boast of such knowledge, and feign
dwellings and habitations for the soul, are wont to provoke
either laughter or disgust. So, again, when we look at the sun,
we imagine that it is distant from us about two hundred feet ;
this error does not lie solely in this fancy, but in the fact
that, while we thus imagine, we do not know the sun's true
distance or the cause of the fancy. For although we afterwards
learn, that the sun is distant from us more than six hundred of
the earth's diameters, we none the less shall fancy it to be near
; for we do not imagine the sun as near us, because we are
ignorant of its true distance, but because the modification of
our body involves the essence of the sun, in so far as our said
body is affected thereby.
PROP. XXXVI. Inadequate and confused ideas follow by the same
necessity, as adequate or clear and distinct ideas.
Proof.-All ideas are in God (I. xv.), and in so far as they
are referred to God are true (II. xxxii.) and (II. vii. Coroll.)
adequate ; therefore there are no ideas confused or inadequate,
except in respect to a particular mind (cf. II. xxiv. and
xxviii.) ; therefore all ideas, whether adequate or inadequate,
follow by the same necessity (II. vi.). Q.E.D.
PROP. XXXVII. That which is common to all (cf. Lemma II.,
above), and which is equally in a part and in the whole, does not
constitute the essence of any particular thing.
Proof.-If this be denied, conceive, if possible, that it
constitutes the essence of some particular thing ; for instance,
the essence of B. Then (II. Def. ii.) it cannot without B either
exist or be conceived ; but this is against our hypothesis.
Therefore it does not appertain to B's essence, nor does it
constitute the essence of any particular thing. Q.E.D.
PROP. XXXVIII. Those things, which are common to all, and which
are equally in a part and in the whole, cannot be conceived
Proof.-Let A be something, which is common to all bodies, and
which is equally present in the part of any given body and in the
whole. I say A cannot be conceived except adequately. For the
idea thereof in God will necessarily be adequate (II. vii.
Coroll.), both in so far as God has the idea of the human body,
and also in so far as he has the idea of the modifications of the
human body, which (II. xvi., xxv., xxvii.) involve in part the
nature of the human body and the nature of external bodies ; that
is (II. xii., xiii.), the idea in God will necessarily be
adequate, both in so far as he constitutes the human mind, and in
so far as he has the ideas, which are in the human mind.
Therefore the mind (II. xi. Coroll.) necessarily perceives A
adequately, and has this adequate perception, both in so far as
it perceives itself, and in so far as it perceives its own or any
external body, nor can A be conceived in any other manner.
Corollary-Hence it follows that there are certain ideas or
notions common to all men ; for (by Lemma ii.) all bodies agree
in certain respects, which (by the foregoing Prop.) must be
adequately or clearly and distinctly perceived by all.
PROP. XXXIX. That, which is common to and a property of the
human body and such other bodies as are wont to affect the human
body, and which is present equally in each part of either, or in
the whole, will be represented by an adequate idea in the mind.
Proof.-If A be that, which is common to and a property of the
human body and external bodies, and equally present in the human
body and in the said external bodies, in each part of each
external body and in the whole, there will be an adequate idea of
A in God (II. vii. Coroll.), both in so far as he has the idea of
the human body, and in so far as he has the ideas of the given
external bodies. Let it now be granted, that the human body is
affected by an external body through that, which it has in common
therewith, namely, A ; the idea of this modification will involve
the property A (II. xvi.), and therefore (II. vii. Coroll.) the
idea of this modification, in so far as it involves the property
A, will be adequate in God, in so far as God is affected by the
idea of the human body ; that is (II. xiii.), in so far as he
constitutes the nature of the human mind ; therefore (II. xi.
Coroll.) this idea is also adequate in the human mind. Q.E.D.
Corollary.-Hence it follows that the mind is fitted to
perceive adequately more things, in proportion as its body has
more in common with other bodies.
PROP. XL. Whatsoever ideas in the mind follow from ideas which
are therein adequate, are also themselves adequate.
Proof.-This proposition is self-evident. For when we say
that an idea in the human mind follows from ideas which are
therein adequate, we say, in other words (II. xi. Coroll.), that
an idea is in the divine intellect, whereof God is the cause, not
in so far as he is infinite, nor in so far as he is affected by
the ideas of very many particular things, but only in so far as
he constitutes the essence of the human mind.
Note I.-I have thus set forth the cause of those notions,
which are common to all men, and which form the basis of our
ratiocination. But there are other causes of certain axioms or
notions, which it would be to the purpose to set forth by this
method of ours ; for it would thus appear what notions are more
useful than others, and what notions have scarcely any use at
all. Furthermore, we should see what notions are common to all
men, and what notions are only clear and distinct to those who
are unshackled by prejudice, and we should detect those which are
ill-founded. Again we should discern whence the notions called
secondary derived their origin, and consequently the axioms on
which they are founded, and other points of interest connected
with these questions. But I have decided to pass over the
subject here, partly because I have set it aside for another
treatise, partly because I am afraid of wearying the reader by
too great prolixity. Nevertheless, in order not to omit anything
necessary to be known, I will briefly set down the causes, whence
are derived the terms styled transcendental, such as Being,
Thing, Something. These terms arose from the fact, that the
human body, being limited, is only capable of distinctly forming
a certain number of images (what an image is I explained in the
II. xvii. note) within itself at the same time ; if this number
be exceeded, the images will begin to be confused ; if this
number of images, of which the body is capable of forming
distinctly within itself, be largely exceeded, all will become
entirely confused one with another. This being so, it is evident
(from II. Prop. xvii. Coroll., and xviii.) that the human mind
can distinctly imagine as many things simultaneously, as its body
can form images simultaneously. When the images become quite
confused in the body, the mind also imagines all bodies
confusedly without any distinction, and will comprehend them, as
it were, under one attribute, namely, under the attribute of
Being, Thing, &c. The same conclusion can be drawn from the fact
that images are not always equally vivid, and from other
analogous causes, which there is no need to explain here ; for
the purpose which we have in view it is sufficient for us to
consider one only. All may be reduced to this, that these terms
represent ideas in the highest degree confused. From similar
causes arise those notions, which we call general, such as man,
horse, dog, &c. They arise, to wit, from the fact that so many
images, for instance, of men, are formed simultaneously in the
human mind, that the powers of imagination break down, not indeed
utterly, but to the extent of the mind losing count of small
differences between individuals (e.g. colour, size, &c.) and
their definite number, and only distinctly imagining that, in
which all the individuals, in so far as the body is affected by
them, agree ; for that is the point, in which each of the said
individuals chiefly affected the body ; this the mind expresses
by the name man, and this it predicates of an infinite number of
particular individuals. For, as we have said, it is unable to
imagine the definite number of individuals. We must, however,
bear in mind, that these general notions are not formed by all
men in the same way, but vary in each individual according as the
point varies, whereby the body has been most often affected and
which the mind most easily imagines or remembers. For instance,
those who have most often regarded with admiration the stature of
man, will by the name of man understand an animal of erect
stature ; those who have been accustomed to regard some other
attribute, will form a different general image of man, for
instance, that man is a laughing animal, a two-footed animal
without feathers, a rational animal, and thus, in other cases,
everyone will form general images of things according to the
habit of his body.
It is thus not to be wondered at, that among philosophers,
who seek to explain things in nature merely by the images formed
of them, so many controversies should have arisen.
Note II.-From all that has been said above it is clear, that
we, in many cases, perceive and form our general notions :-(1.)
From particular things represented to our intellect
fragmentarily, confusedly, and without order through our senses
(II. xxix. Coroll.) ; I have settled to call such perceptions by
the name of knowledge from the mere suggestions of experience.4
(2.) From symbols, e.g., from the fact of having read or heard
certain words we remember things and form certain ideas
concerning them, similar to those through which we imagine things
(II. xviii. note). I shall call both these ways of regarding
things knowledge of the first kind, opinion, or imagination.
(3.) From the fact that we have notions common to all men, and
adequate ideas of the properties of things (II. xxxviii. Coroll.,
xxxix. and Coroll. and xl.) ; this I call reason and knowledge of
the second kind. Besides these two kinds of knowledge, there is,
as I will hereafter show, a third kind of knowledge, which we
will call intuition. This kind of knowledge proceeds from an
adequate idea of the absolute essence of certain attributes of
God to the adequate knowledge of the essence of things. I will
illustrate all three kinds of knowledge by a single example.
Three numbers are given for finding a fourth, which shall be to
the third as the second is to the first. Tradesmen without
hesitation multiply the second by the third, and divide the
product by the first ; either because they have not forgotten the
rule which they received from a master without any proof, or
because they have often made trial of it with simple numbers, or
by virtue of the proof of the nineteenth proposition of the
seventh book of Euclid, namely, in virtue of the general property
But with very simple numbers there is no need of this. For
instance, one, two, three, being given, everyone can see that the
fourth proportional is six ; and this is much clearer, because we
infer the fourth number from an intuitive grasping of the ratio,
which the first bears to the second.
PROP. XLI. Knowledge of the first kind is the only source of
falsity, knowledge of the second and third kinds is necessarily
Proof.-To knowledge of the first kind we have (in the
foregoing note) assigned all those ideas, which are inadequate
and confused ; therefore this kind of knowledge is the only
source of falsity (II. xxxv.). Furthermore, we assigned to the
second and third kinds of knowledge those ideas which are
adequate ; therefore these kinds are necessarily true (II.
PROP. XLII. Knowledge of the second and third kinds, not
knowledge of the first kind, teaches us to distinguish the true
from the false.
Proof.-This proposition is self-evident. He, who knows how
to distinguish between true and false, must have an adequate idea
of true and false. That is (II. xl., note ii.), he must know the
true and the false by the second or third kind of knowledge.
PROP. XLIII. He, who has a true idea, simultaneously knows that
he has a true idea, and cannot doubt of the truth of the thing
Proof.-A true idea in us is an idea which is adequate in God,
in so far as he is displayed through the nature of the human mind
(II. xi. Coroll.). Let us suppose that there is in God, in so
far as he is displayed through the human mind, an adequate idea,
A. The idea of this idea must also necessarily be in God, and be
referred to him in the same way as the idea A (by II. xx.,
whereof the proof is of universal application). But the idea A
is supposed to be referred to God, in so far as he is displayed
through the human mind ; therefore, the idea of the idea A must
be referred to God in the same manner ; that is (by II. xi.
Coroll.), the adequate idea of the idea A will be in the mind,
which has the adequate idea A ; therefore he, who has an adequate
idea or knows a thing truly (II. xxxiv.), must at the same time
have an adequate idea or true knowledge of his knowledge ; that
is, obviously, he must be assured. Q.E.D.
Note.-I explained in the note to II. xxi. what is meant by
the idea of an idea ; but we may remark that the foregoing
proposition is in itself sufficiently plain. No one, who has a
true idea, is ignorant that a true idea involves the highest
certainty. For to have a true idea is only another expression
for knowing a thing perfectly, or as well as possible. No one,
indeed, can doubt of this, unless he thinks that an idea is
something lifeless, like a picture on a panel, and not a mode of
thinking-namely, the very act of understanding. And who, I ask,
can know that he understands anything, unless he do first
understand it? In other words, who can know that he is sure of a
thing, unless he be first sure of that thing? Further, what can
there be more clear, and more certain, than a true idea as a
standard of truth? Even as light displays both itself and
darkness, so is truth a standard both of itself and of falsity.
I think I have thus sufficiently answered these
questions-namely, if a true idea is distinguished from a false
idea, only in so far as it is said to agree with its object, a
true idea has no more reality or perfection than a false idea
(since the two are only distinguished by an extrinsic mark) ;
consequently, neither will a man who has a true idea have any
advantage over him who has only false ideas. Further, how comes
it that men have false ideas? Lastly, how can anyone be sure,
that he has ideas which agree with their objects? These
questions, I repeat, I have, in my opinion, sufficiently
answered. The difference between a true idea and a false idea is
plain : from what was said in II. xxxv., the former is related to
the latter as being is to not-being. The causes of falsity I
have set forth very clearly in II. xix. and II. xxxv. with the
note. From what is there stated, the difference between a man
who has true ideas, and a man who has only false ideas, is made
apparent. As for the last question-as to how a man can be sure
that he has ideas that agree with their objects, I have just
pointed out, with abundant clearness, that his knowledge arises
from the simple fact, that he has an idea which corresponds with
its object-in other words, that truth is its own standard. We
may add that our mind, in so far as it perceives things truly, is
part of the infinite intellect of God (II. xi. Coroll.) ;
therefore, the clear and distinct ideas of the mind are as
necessarily true as the ideas of God.
PROP. XLIV. It is not in the nature of reason to regard things
as contingent, but as necessary.
Proof.-It is in the nature of reason to perceive things truly
(II. xli.), namely (I. Ax. vi.), as they are in themselves-that
is (I. xxix.), not as contingent, but as necessary. Q.E.D.
Corollary I.-Hence it follows, that it is only through our
imagination that we consider things, whether in respect to the
future or the past, as contingent.
Note.-How this way of looking at things arises, I will
briefly explain. We have shown above (II. xvii. and Coroll.)
that the mind always regards things as present to itself, even
though they be not in existence, until some causes arise which
exclude their existence and presence. Further (II. xviii.), we
showed that, if the human body has once been affected by two
external bodies simultaneously, the mind, when it afterwards
imagines one of the said external bodies, will straightway
remember the other-that is, it will regard both as present to
itself, unless there arise causes which exclude their existence
and presence. Further, no one doubts that we imagine time, from
the fact that we imagine bodies to be moved some more slowly than
others, some more quickly, some at equal speed. Thus, let us
suppose that a child yesterday saw Peter for the first time in
the morning, Paul at noon, and Simon in the evening ; then, that
today he again sees Peter in the morning. It is evident, from
II. Prop. xviii., that, as soon as he sees the morning light, he
will imagine that the sun will traverse the same parts of the
sky, as it did when he saw it on the preceding day ; in other
words, he will imagine a complete day, and, together with his
imagination of the morning, he will imagine Peter ; with noon, he
will imagine Paul ; and with evening, he will imagine Simon-that
is, he will imagine the existence of Paul and Simon in relation
to a future time ; on the other hand, if he sees Simon in the
evening, he will refer Peter and Paul to a past time, by
imagining them simultaneously with the imagination of a past
time. If it should at any time happen, that on some other
evening the child should see James instead of Simon, he will, on
the following morning, associate with his imagination of evening
sometimes Simon, sometimes James, not both together : for the
child is supposed to have seen, at evening, one or other of them,
not both together. His imagination will therefore waver ; and,
with the imagination of future evenings, he will associate first
one, then the other-that is, he will imagine them in the future,
neither of them as certain, but both as contingent. This
wavering of the imagination will be the same, if the imagination
be concerned with things which we thus contemplate, standing in
relation to time past or time present : consequently, we may
imagine things as contingent, whether they be referred to time
present, past, or future.
Corollary II.-It is in the nature of reason to perceive
things under a certain form of eternity (sub quādam ęternitatis
Proof.-It is in the nature of reason to regard things, not as
contingent, but as necessary (II. xliv.). Reason perceives this
necessity of things (II. xli.) truly-that is (I. Ax. vi.), as it
is in itself. But (I. xvi.) this necessity of things is the very
necessity of the eternal nature of God ; therefore, it is in the
nature of reason to regard things under this form of eternity.
We may add that the bases of reason are the notions (II.
xxxviii.), which answer to things common to all, and which (II.
xxxvii.) do not answer to the essence of any particular thing :
which must therefore be conceived without any relation to time,
under a certain form of eternity.
PROP. XLV. Every idea of every body, or of every particular
thing actually existing, necessarily involves the eternal and
infinite essence of God.
Proof.-The idea of a particular thing actually existing
necessarily involves both the existence and the essence of the
said thing (II. viii.). Now particular things cannot be
conceived without God (I. xv.) ; but, inasmuch as (II. vi.) they
have God for their cause, in so far as he is regarded under the
attribute of which the things in question are modes, their ideas
must necessarily involve (I. Ax. iv.) the conception of the
attributes of those ideas-that is (I. vi.), the eternal and
infinite essence of God. Q.E.D.
Note.-By existence I do not here mean duration-that is,
existence in so far as it is conceived abstractedly, and as a
certain form of quantity. I am speaking of the very nature of
existence, which is assigned to particular things, because they
follow in infinite numbers and in infinite ways from the eternal
necessity of God's nature (I. xvi.). I am speaking, I repeat, of
the very existence of particular things, in so far as they are in
God. For although each particular thing be conditioned by
another particular thing to exist in a given way, yet the force
whereby each particular thing perseveres in existing follows from
the eternal necessity of God's nature (cf. I. xxiv. Coroll.).
PROP. XLVI. The knowledge of the eternal and infinite essence of
God which every idea involves is adequate and perfect.
Proof.-The proof of the last proposition is universal ; and
whether a thing be considered as a part or a whole, the idea
thereof, whether of the whole or of a part (by the last Prop.),
will involve God's eternal and infinite essence. Wherefore,
that, which gives knowledge of the eternal and infinite essence
of God, is common to all, and is equally in the part and in the
whole ; therefore (II. xxxviii.) this knowledge will be adequate.
PROP. XLVII. The human mind has an adequate knowledge of the
eternal and infinite essence of God.
Proof.-The human mind has ideas (II. xxii.), from which (II.
xxiii.) it perceives itself and its own body (II. xix.) and
external bodies (II. xvi. Coroll. i. and II. xvii.) as actually
existing ; therefore (II. xlv. and xlvi.) it has an adequate
knowledge of the eternal and infinite essence of God. Q.E.D.
Note.-Hence we see, that the infinite essence and the
eternity of God are known to all. Now as all things are in God,
and are conceived through God, we can from this knowledge infer
many things, which we may adequately know, and we may form that
third kind of knowledge of which we spoke in the note to II. xl.,
and of the excellence and use of which we shall have occasion to
speak in Part V. Men have not so clear a knowledge of God as
they have of general notions, because they are unable to imagine
God as they do bodies, and also because they have associated the
name God with images of things that they are in the habit of
seeing, as indeed they can hardly avoid doing, being, as they
are, men, and continually affected by external bodies. Many
errors, in truth, can be traced to this head, namely, that we do
not apply names to things rightly. For instance, when a man says
that the lines drawn from the centre of a circle to its
circumference are not equal, he then, at all events, assuredly
attaches a meaning to the word circle different from that
assigned by mathematicians. So again, when men make mistakes in
calculation, they have one set of figures in their mind, and
another on the paper. If we could see into their minds, they do
not make a mistake ; they seem to do so, because we think, that
they have the same numbers in their mind as they have on the
paper. If this were not so, we should not believe them to be in
error, any more than I thought that a man was in error, whom I
lately heard exclaiming that his entrance hall had flown into a
neighbour's hen, for his meaning seemed to me sufficiently clear.
Very many controversies have arisen from the fact, that men do
not rightly explain their meaning, or do not rightly interpret
the meaning of others. For, as a matter of fact, as they flatly
contradict themselves, they assume now one side, now another, of
the argument, so as to oppose the opinions, which they consider
mistaken and absurd in their opponents.
PROP. XLVIII. In the mind there is no absolute or free will ;
but the mind is determined to wish this or that by a cause, which
has also been determined by another cause, and this last by
another cause, and so on to infinity.
Proof.-The mind is a fixed and definite mode of thought (II.
xi.), therefore it cannot be the free cause of its actions (I.
xvii. Coroll. ii.) ; in other words, it cannot have an absolute
faculty of positive or negative volition ; but (by I. xxviii.) it
must be determined by a cause, which has also been determined by
another cause, and this last by another, &c. Q.E.D.
Note.-In the same way it is proved, that there is in the mind
no absolute faculty of understanding, desiring, loving, &c.
Whence it follows, that these and similar faculties are either
entirely fictitious, or are merely abstract and general terms,
such as we are accustomed to put together from particular things.
Thus the intellect and the will stand in the same relation to
this or that idea, or this or that volition, as "lapidity" to
this or that stone, or as "man" to Peter and Paul. The cause
which leads men to consider themselves free has been set forth in
the Appendix to Part I. But, before I proceed further, I would
here remark that, by the will to affirm and decide, I mean the
faculty, not the desire. I mean, I repeat, the faculty, whereby
the mind affirms or denies what is true or false, not the desire,
wherewith the mind wishes for or turns away from any given thing.
After we have proved, that these faculties of ours are general
notions, which cannot be distinguished from the particular
instances on which they are based, we must inquire whether
volitions themselves are anything besides the ideas of things.
We must inquire, I say, whether there is in the mind any
affirmation or negation beyond that, which the idea, in so far as
it is an idea, involves. On which subject see the following
proposition, and II. Def. iii., lest the idea of pictures should
suggest itself. For by ideas I do not mean images such as are
formed at the back of the eye, or in the midst of the brain, but
the conceptions of thought.
PROP. XLIX. There is in the mind no volition or affirmation and
negation, save that which an idea, inasmuch as it is an idea,
Proof.-There is in the mind no absolute faculty of positive
or negative volition, but only particular volitions, namely, this
or that affirmation, and this or that negation. Now let us
conceive a particular volition, namely, the mode of thinking
whereby the mind affirms, that the three interior angles of a
triangle are equal to two right angles. This affirmation
involves the conception or idea of a triangle, that is, without
the idea of a triangle it cannot be conceived. It is the same
thing to say, that the concept A must involve the concept B, as
it is to say, that A cannot be conceived without B. Further,
this affirmation cannot be made (II. Ax. iii.) without the idea
of a triangle. Therefore, this affirmation can neither be nor be
conceived, without the idea of a triangle. Again, this idea of a
triangle must involve this same affirmation, namely, that its
three interior angles are equal to two right angles. Wherefore,
and vice versā, this idea of a triangle can neither be nor be
conceived without this affirmation, therefore, this affirmation
belongs to the essence of the idea of a triangle, and is nothing
besides. What we have said of this volition (inasmuch as we have
selected it at random) may be said of any other volition, namely,
that it is nothing but an idea. Q.E.D.
Corollary.-Will and understanding are one and the same.
Proof.-Will and understanding are nothing beyond the
individual volitions and ideas (II. xlviii. and note). But a
particular volition and a particular idea are one and the same
(by the foregoing Prop.) ; therefore, will and understanding are
one and the same. Q.E.D.
Note.-We have thus removed the cause which is commonly
assigned for error. For we have shown above, that falsity
consists solely in the privation of knowledge involved in ideas
which are fragmentary and confused. Wherefore, a false idea,
inasmuch as it is false, does not involve certainty. When we
say, then, that a man acquiesces in what is false, and that he
has no doubts on the subject, we do not say that he is certain,
but only that he does not doubt, or that he acquiesces in what is
false, inasmuch as there are no reasons, which should cause his
imagination to waver (see II. xliv. note). Thus, although the
man be assumed to acquiesce in what is false, we shall never say
that he is certain. For by certainty we mean something positive
(II. xliii. and note), not merely the absence of doubt.
However, in order that the foregoing proposition may be fully
explained, I will draw attention to a few additional points, and
I will furthermore answer the objections which may be advanced
against our doctrine. Lastly, in order to remove every scruple,
I have thought it worth while to point out some of the
advantages, which follow therefrom. I say "some," for they will
be better appreciated from what we shall set forth in the fifth
I begin, then, with the first point, and warn my readers to
make an accurate distinction between an idea, or conception of
the mind, and the images of things which we imagine. It is
further necessary that they should distinguish between idea and
words, whereby we signify things. These three-namely, images,
words, and ideas-are by many persons either entirely confused
together, or not distinguished with sufficient accuracy or care,
and hence people are generally in ignorance, how absolutely
necessary is a knowledge of this doctrine of the will, both for
philosophic purposes and for the wise ordering of life. Those
who think that ideas consist in images which are formed in us by
contact with external bodies, persuade themselves that the ideas
of those things, whereof we can form no mental picture, are not
ideas, but only figments, which we invent by the free decree of
our will ; they thus regard ideas as though they were inanimate
pictures on a panel, and, filled with this misconception, do not
see that an idea, inasmuch as it is an idea, involves an
affirmation or negation. Again, those who confuse words with
ideas, or with the affirmation which an idea involves, think that
they can wish something contrary to what they feel, affirm, or
deny. This misconception will easily be laid aside by one, who
reflects on the nature of knowledge, and seeing that it in no
wise involves the conception of extension, will therefore clearly
understand, that an idea (being a mode of thinking) does not
consist in the image of anything, nor in words. The essence of
words and images is put together by bodily motions, which in no
wise involve the conception of thought.
These few words on this subject will suffice : I will
therefore pass on to consider the objections, which may be raised
against our doctrine. Of these, the first is advanced by those,
who think that the will has a wider scope than the understanding,
and that therefore it is different therefrom. The reason for
their holding the belief, that the will has wider scope than the
understanding, is that they assert, that they have no need of an
increase in their faculty of assent, that is of affirmation or
negation, in order to assent to an infinity of things which we do
not perceive, but that they have need of an increase in their
faculty of understanding. The will is thus distinguished from
the intellect, the latter being finite and the former infinite.
Secondly, it may be objected that experience seems to teach us
especially clearly, that we are able to suspend our judgment
before assenting to things which we perceive ; this is confirmed
by the fact that no one is said to be deceived, in so far as he
perceives anything, but only in so far as he assents or dissents.
For instance, he who feigns a winged horse, does not
therefore admit that a winged horse exists ; that is, he is not
deceived, unless he admits in addition that a winged horse does
exist. Nothing therefore seems to be taught more clearly by
experience, than that the will or faculty of assent is free and
different from the faculty of understanding. Thirdly, it may be
objected that one affirmation does not apparently contain more
reality than another ; in other words, that we do not seem to
need for affirming, that what is true is true, any greater power
than for affirming, that what is false is true. We have,
however, seen that one idea has more reality or perfection than
another, for as objects are some more excellent than others, so
also are the ideas of them some more excellent than others ; this
also seems to point to a difference between the understanding and
the will. Fourthly, it may be objected, if man does not act from
free will, what will happen if the incentives to action are
equally balanced, as in the case of Buridan's ass? Will he
perish of hunger and thirst? If I say that he would, I shall
seem to have in my thoughts an ass or the statue of a man rather
than an actual man. If I say that he would not, he would then
determine his own action, and would consequently possess the
faculty of going and doing whatever he liked. Other objections
might also be raised, but, as I am not bound to put in evidence
everything that anyone may dream, I will only set myself to the
task of refuting those I have mentioned, and that as briefly as
To the first objection I answer, that I admit that the will
has a wider scope than the understanding, if by the understanding
be meant only clear and distinct ideas ; but I deny that the will
has a wider scope than the perceptions, and the faculty of
forming conceptions ; nor do I see why the faculty of volition
should be called infinite, any more than the faculty of feeling :
for, as we are able by the same faculty of volition to affirm an
infinite number of things (one after the other, for we cannot
affirm an infinite number simultaneously), so also can we, by the
same faculty of feeling, feel or perceive (in succession) an
infinite number of bodies. If it be said that there is an
infinite number of things which we cannot perceive, I answer,
that we cannot attain to such things by any thinking, nor,
consequently, by any faculty of volition. But, it may still be
urged, if God wished to bring it about that we should perceive
them, he would be obliged to endow us with a greater faculty of
perception, but not a greater faculty of volition than we have
already. This is the same as to say that, if God wished to bring
it about that we should understand an infinite number of other
entities, it would be necessary for him to give us a greater
understanding, but not a more universal idea of entity than that
which we have already, in order to grasp such infinite entities.
We have shown that will is a universal entity or idea, whereby we
explain all particular volitions-in other words, that which is
common to all such volitions.
As, then, our opponents maintain that this idea, common or
universal to all volitions, is a faculty, it is little to be
wondered at that they assert, that such a faculty extends itself
into the infinite, beyond the limits of the understanding : for
what is universal is predicated alike of one, of many, and of an
infinite number of individuals.
To the second objection I reply by denying, that we have a
free power of suspending our judgment : for, when we say that
anyone suspends his judgment, we merely mean that he sees, that
he does not perceive the matter in question adequately.
Suspension of judgment is, therefore, strictly speaking, a
perception, and not free will. In order to illustrate the point,
let us suppose a boy imagining a horse, and perceive nothing
else. Inasmuch as this imagination involves the existence of the
horse (II. xvii. Coroll.), and the boy does not perceive anything
which would exclude the existence of the horse, he will
necessarily regard the horse as present : he will not be able to
doubt of its existence, although he be not certain thereof. We
have daily experience of such a state of things in dreams ; and I
do not suppose that there is anyone, who would maintain that,
while he is dreaming, he has the free power of suspending his
judgment concerning the things in his dream, and bringing it
about that he should not dream those things, which he dreams that
he sees ; yet it happens, notwithstanding, that even in dreams we
suspend our judgment, namely, when we dream that we are dreaming.
Further, I grant that no one can be deceived, so far as
actual perception extends-that is, I grant that the mind's
imaginations, regarded in themselves, do not involve error (II.
xvii. note) ; but I deny, that a man does not, in the act of
perception, make any affirmation. For what is the perception of
a winged horse, save affirming that a horse has wings? If the
mind could perceive nothing else but the winged horse, it would
regard the same as present to itself : it would have no reasons
for doubting its existence, nor any faculty of dissent, unless
the imagination of a winged horse be joined to an idea which
precludes the existence of the said horse, or unless the mind
perceives that the idea which it possess of a winged horse is
inadequate, in which case it will either necessarily deny the
existence of such a horse, or will necessarily be in doubt on the
I think that I have anticipated my answer to the third
objection, namely, that the will is something universal which is
predicated of all ideas, and that it only signifies that which is
common to all ideas, namely, an affirmation, whose adequate
essence must, therefore, in so far as it is thus conceived in the
abstract, be in every idea, and be, in this respect alone, the
same in all, not in so far as it is considered as constituting
the idea's essence : for, in this respect, particular
affirmations differ one from the other, as much as do ideas. For
instance, the affirmation which involves the idea of a circle,
differs from that which involves the idea of a triangle, as much
as the idea of a circle differs from the idea of a triangle.
Further, I absolutely deny, that we are in need of an equal
power of thinking, to affirm that that which is true is true, and
to affirm that that which is false is true. These two
affirmations, if we regard the mind, are in the same relation to
one another as being and not-being ; for there is nothing
positive in ideas, which constitutes the actual reality of
falsehood (II. xxxv. note, and xlvii. note).
We must therefore conclude, that we are easily deceived, when
we confuse universals with singulars, and the entities of reason
and abstractions with realities. As for the fourth objection, I
am quite ready to admit, that a man placed in the equilibrium
described (namely, as perceiving nothing but hunger and thirst,
a certain food and a certain drink, each equally distant from
him) would die of hunger and thirst. If I am asked, whether such
an one should not rather be considered an ass than a man ; I
answer, that I do not know, neither do I know how a man should be
considered, who hangs himself, or how we should consider
children, fools, madmen, &c.
It remains to point out the advantages of a knowledge of this
doctrine as bearing on conduct, and this may be easily gathered
from what has been said. The doctrine is good,
1. Inasmuch as it teaches us to act solely according to the
decree of God, and to be partakers in the Divine nature, and so
much the more, as we perform more perfect actions and more and
more understand God. Such a doctrine not only completely
tranquilizes our spirit, but also shows us where our highest
happiness or blessedness is, namely, solely in the knowledge of
God, whereby we are led to act only as love and piety shall bid
us. We may thus clearly understand, how far astray from a true
estimate of virtue are those who expect to be decorated by God
with high rewards for their virtue, and their best actions, as
for having endured the direst slavery ; as if virtue and the
service of God were not in itself happiness and perfect freedom.
2. Inasmuch as it teaches us, how we ought to conduct
ourselves with respect to the gifts of fortune, or matters which
are not in our power, and do not follow from our nature. For it
shows us, that we should await and endure fortune's smiles or
frowns with an equal mind, seeing that all things follow from the
eternal decree of God by the same necessity, as it follows from
the essence of a triangle, that the three angles are equal to two
3. This doctrine raises social life, inasmuch as it teaches
us to hate no man, neither to despise, to deride, to envy, or to
be angry with any. Further, as it tells us that each should be
content with his own, and helpful to his neighbour, not from any
womanish pity, favour, or superstition, but solely by the
guidance of reason, according as the time and occasion demand, as
I will show in Part III.
4. Lastly, this doctrine confers no small advantage on the
commonwealth ; for it teaches how citizens should be governed and
led, not so as to become slaves, but so that they may freely do
whatsoever things are best.
I have thus fulfilled the promise made at the beginning of
this note, and I thus bring the second part of my treatise to a
close. I think I have therein explained the nature and
properties of the human mind at sufficient length, and,
considering the difficulty of the subject, with sufficient
clearness. I have laid a foundation, whereon may be raised many
excellent conclusions of the highest utility and most necessary
to be known, as will, in what follows, be partly made plain.
ON THE ORIGIN AND NATURE OF THE EMOTIONS
Most writers on the emotions and on human conduct seem to be
treating rather of matters outside nature than of natural
phenomena following nature's general laws. They appear to
conceive man to be situated in nature as a kingdom within a
kingdom : for they believe that he disturbs rather than follows
nature's order, that he has absolute control over his actions,
and that he is determined solely by himself. They attribute
human infirmities and fickleness, not to the power of nature in
general, but to some mysterious flaw in the nature of man, which
accordingly they bemoan, deride, despise, or, as usually happens,
abuse : he, who succeeds in hitting off the weakness of the human
mind more eloquently or more acutely than his fellows, is looked
upon as a seer. Still there has been no lack of very excellent
men (to whose toil and industry I confess myself much indebted),
who have written many noteworthy things concerning the right way
of life, and have given much sage advice to mankind. But no one,
so far as I know, has defined the nature and strength of the
emotions, and the power of the mind against them for their
I do not forget, that the illustrious Descartes, though he
believed, that the mind has absolute power over its actions,
strove to explain human emotions by their primary causes, and, at
the same time, to point out a way, by which the mind might attain
to absolute dominion over them. However, in my opinion, he
accomplishes nothing beyond a display of the acuteness of his own
great intellect, as I will show in the proper place. For the
present I wish to revert to those, who would rather abuse or
deride human emotions than understand them. Such persons will,
doubtless think it strange that I should attempt to treat of
human vice and folly geometrically, and should wish to set forth
with rigid reasoning those matters which they cry out against as
repugnant to reason, frivolous, absurd, and dreadful. However,
such is my plan. Nothing comes to pass in nature, which can be
set down to a flaw therein ; for nature is always the same, and
everywhere one and the same in her efficacy and power of action ;
that is, nature's laws and ordinances, whereby all things come to
pass and change from one form to another, are everywhere and
always the same ; so that there should be one and the same method
of understanding the nature of all things whatsoever, namely,
through nature's universal laws and rules. Thus the passions of
hatred, anger, envy, and so on, considered in themselves, follow
from this same necessity and efficacy of nature ; they answer to
certain definite causes, through which they are understood, and
possess certain properties as worthy of being known as the
properties of anything else, whereof the contemplation in itself
affords us delight. I shall, therefore, treat of the nature and
strength of the emotions according to the same method, as I
employed heretofore in my investigations concerning God and the
mind. I shall consider human actions and desires in exactly the
same manner, as though I were concerned with lines, planes, and
I. By an adequate cause, I mean a cause through which its effect
can be clearly and distinctly perceived. By an inadequate or
partial cause, I mean a cause through which, by itself, its
effect cannot be understood.
II. I say that we act when anything takes place, either within
us or externally to us, whereof we are the adequate cause ; that
is (by the foregoing definition) when through our nature
something takes place within us or externally to us, which can
through our nature alone be clearly and distinctly understood.
On the other hand, I say that we are passive as regards something
when that something takes place within us, or follows from our
nature externally, we being only the partial cause.
III. By emotion I mean the modifications of the body, whereby
the active power of the said body is increased or diminished,
aided or constrained, and also the ideas of such modifications.
N.B. If we can be the adequate cause of any of these
modifications, I then call the emotion an activity, otherwise I
call it a passion, or state wherein the mind is passive.
I. The human body can be affected in many ways, whereby its
power of activity is increased or diminished, and also in other
ways which do not render its power of activity either greater or
N.B. This postulate or axiom rests on Postulate i. and
Lemmas v. and vii., which see after II. xiii.
II. The human body can undergo many changes, and, nevertheless,
retain the impressions or traces of objects (cf. II. Post. v.),
and, consequently, the same images of things (see note II.
PROP. I. Our mind is in certain cases active, and in certain
cases passive. In so far as it has adequate ideas it is
necessarily active, and in so far as it has inadequate ideas, it
is necessarily passive.
Proof.-In every human mind there are some adequate ideas, and
some ideas that are fragmentary and confused (II. xl. note).
Those ideas which are adequate in the mind are adequate also in
God, inasmuch as he constitutes the essence of the mind (II. xl.
Coroll.), and those which are inadequate in the mind are likewise
(by the same Coroll.) adequate in God, not inasmuch as he
contains in himself the essence of the given mind alone, but as
he, at the same time, contains the minds of other things. Again,
from any given idea some effect must necessarily follow (I. 36) ;
of this effect God is the adequate cause (III. Def. i.), not
inasmuch as he is infinite, but inasmuch as he is conceived as
affected by the given idea (II. ix.). But of that effect whereof
God is the cause, inasmuch as he is affected by an idea which is
adequate in a given mind, of that effect, I repeat, the mind in
question is the adequate cause (II. xi. Coroll.). Therefore our
mind, in so far as it has adequate ideas (III. Def. ii.), is in
certain cases necessarily active ; this was our first point.
Again, whatsoever necessarily follows from the idea which is
adequate in God, not by virtue of his possessing in himself the
mind of one man only, but by virtue of his containing, together
with the mind of that one man, the minds of other things also, of
such an effect (II. xi. Coroll.) the mind of the given man is not
an adequate, but only a partial cause ; thus (III. Def. ii.) the
mind, inasmuch as it has inadequate ideas, is in certain cases
necessarily passive ; this was our second point. Therefore our
mind, &c. Q.E.D.
Corollary.-Hence it follows that the mind is more or less
liable to be acted upon, in proportion as it possesses inadequate
ideas, and, contrariwise, is more or less active in proportion as
it possesses adequate ideas.
PROP. II. Body cannot determine mind to think, neither can mind
determine body to motion or rest or any state different from
these, if such there be.
Proof.-All modes of thinking have for their cause God, by
virtue of his being a thinking thing, and not by virtue of his
being displayed under any other attribute (II. vi.). That,
therefore, which determines the mind to thought is a mode of
thought, and not a mode of extension ; that is (II. Def. i.), it
is not body. This was our first point. Again, the motion and
rest of a body must arise from another body, which has also been
determined to a state of motion or rest by a third body, and
absolutely everything which takes place in a body must spring
from God, in so far as he is regarded as affected by some mode of
extension, and not by some mode of thought (II. vi.) ; that is,
it cannot spring from the mind, which is a mode of thought. This
was our second point. Therefore body cannot determine mind, &c.
Note.-This is made more clear by what was said in the note to
II. vii., namely, that mind and body are one and the same thing,
conceived first under the attribute of thought, secondly, under
the attribute of extension. Thus it follows that the order or
concatenation of things is identical, whether nature be conceived
under the one attribute or the other ; consequently the order of
states of activity and passivity in our body is simultaneous in
nature with the order of states of activity and passivity in the
mind. The same conclusion is evident from the manner in which we
proved II. xii.
Nevertheless, though such is the case, and though there be no
further room for doubt, I can scarcely believe, until the fact is
proved by experience, that men can be induced to consider the
question calmly and fairly, so firmly are they convinced that it
is merely at the bidding of the mind, that the body is set in
motion or at rest, or performs a variety of actions depending
solely on the mind's will or the exercise of thought. However,
no one has hitherto laid down the limits to the powers of the
body, that is, no one has as yet been taught by experience what
the body can accomplish solely by the laws of nature, in so far
as she is regarded as extension. No one hitherto has gained such
an accurate knowledge of the bodily mechanism, that he can
explain all its functions ; nor need I call attention to the fact
that many actions are observed in the lower animals, which far
transcend human sagacity, and that somnambulists do many things
in their sleep, which they would not venture to do when awake :
these instances are enough to show, that the body can by the sole
laws of its nature do many things which the mind wonders at.
Again, no one knows how or by what means the mind moves the
body, nor how many various degrees of motion it can impart to the
body, nor how quickly it can move it. Thus, when men say that
this or that physical action has its origin in the mind, which
latter has dominion over the body, they are using words without
meaning, or are confessing in specious phraseology that they are
ignorant of the cause of the said action, and do not wonder at
But, they will say, whether we know or do not know the means
whereby the mind acts on the body, we have, at any rate,
experience of the fact that unless the human mind is in a fit
state to think, the body remains inert. Moreover, we have
experience, that the mind alone can determine whether we speak or
are silent, and a variety of similar states which, accordingly,
we say depend on the mind's decree. But, as to the first point,
I ask such objectors, whether experience does not also teach,
that if the body be inactive the mind is simultaneously unfitted
for thinking? For when the body is at rest in sleep, the mind
simultaneously is in a state of torpor also, and has no power of
thinking, such as it possesses when the body is awake. Again, I
think everyone's experience will confirm the statement, that the
mind is not at all times equally fit for thinking on a given
subject, but according as the body is more or less fitted for
being stimulated by the image of this or that object, so also is
the mind more or less fitted for contemplating the said object.
But, it will be urged, it is impossible that solely from the
laws of nature considered as extended substance, we should be
able to deduce the causes of buildings, pictures, and things of
that kind, which are produced only by human art ; nor would the
human body, unless it were determined and led by the mind, be
capable of building a single temple. However, I have just
pointed out that the objectors cannot fix the limits of the
body's power, or say what can be concluded from a consideration
of its sole nature, whereas they have experience of many things
being accomplished solely by the laws of nature, which they would
never have believed possible except under the direction of mind :
such are the actions performed by somnambulists while asleep, and
wondered at by their performers when awake. I would further call
attention to the mechanism of the human body, which far surpasses
in complexity all that has been put together by human art, not to
repeat what I have already shown, namely, that from nature, under
whatever attribute she be considered, infinite results follow.
As for the second objection, I submit that the world would be
much happier, if men were as fully able to keep silence as they
are to speak. Experience abundantly shows that men can govern
anything more easily than their tongues, and restrain anything
more easily than their appetites ; when it comes about that many
believe, that we are only free in respect to objects which we
moderately desire, because our desire for such can easily be
controlled by the thought of something else frequently
remembered, but that we are by no means free in respect to what
we seek with violent emotion, for our desire cannot then be
allayed with the remembrance of anything else. However, unless
such persons had proved by experience that we do many things
which we afterwards repent of, and again that we often, when
assailed by contrary emotions, see the better and follow the
worse, there would be nothing to prevent their believing that we
are free in all things. Thus an infant believes that of its own
free will it desires milk, an angry child believes that it freely
desires vengeance, a timid child believes that it freely desires
to run away ; further, a drunken man believes that he utters from
the free decision of his mind words which, when he is sober, he
would willingly have withheld : thus, too, a delirious man, a
garrulous woman, a child, and others of like complexion, believe
that they speak from the free decision of their mind, when they
are in reality unable to restrain their impulse to talk.
Experience teaches us no less clearly than reason, that men
believe themselves to be free, simply because they are conscious
of their actions, and unconscious of the causes whereby those
actions are determined ; and, further, it is plain that the
dictates of the mind are but another name for the appetites, and
therefore vary according to the varying state of the body.
Everyone shapes his actions according to his emotion, those who
are assailed by conflicting emotions know not what they wish ;
those who are not attacked by any emotion are readily swayed this
way or that. All these considerations clearly show that a mental
decision and a bodily appetite, or determined state, are
simultaneous, or rather are one and the same thing, which we call
decision, when it is regarded under and explained through the
attribute of thought, and a conditioned state, when it is
regarded under the attribute of extension, and deduced from the
laws of motion and rest. This will appear yet more plainly in
the sequel. For the present I wish to call attention to another
point, namely, that we cannot act by the decision of the mind,
unless we have a remembrance of having done so. For instance, we
cannot say a word without remembering that we have done so.
Again, it is not within the free power of the mind to remember or
forget a thing at will. Therefore the freedom of the mind must
in any case be limited to the power of uttering or not uttering
something which it remembers. But when we dream that we speak,
we believe that we speak from a free decision of the mind, yet we
do not speak, or, if we do, it is by a spontaneous motion of the
body. Again, we dream that we are concealing something, and we
seem to act from the same decision of the mind as that, whereby
we keep silence when awake concerning something we know. Lastly,
we dream that from the free decision of our mind we do something,
which we should not dare to do when awake.
Now I should like to know whether there be in the mind two
sorts of decisions, one sort illusive, and the other sort free?
If our folly does not carry us so far as this, we must
necessarily admit, that the decision of the mind, which is
believed to be free, is not distinguishable from the imagination
or memory, and is nothing more than the affirmation, which an
idea, by virtue of being an idea, necessarily involves (II.
xlix.). Wherefore these decisions of the mind arise in the mind
by the same necessity, as the ideas of things actually existing.
Therefore those who believe, that they speak or keep silence or
act in any way from the free decision of their mind, do but dream
with their eyes open.
PROP. III. The activities of the mind arise solely from adequate
ideas ; the passive states of the mind depend solely on
Proof.-The first element, which constitutes the essence of
the mind, is nothing else but the idea of the actually existent
body (II. xi. and xiii.), which (II. xv.) is compounded of many
other ideas, whereof some are adequate and some inadequate (II.
xxix. Coroll., II. xxxviii. Coroll.). Whatsoever therefore
follows from the nature of mind, and has mind for its proximate
cause, through which it must be understood, must necessarily
follow either from an adequate or from an inadequate idea. But
in so far as the mind (III. i.) has inadequate ideas, it is
necessarily passive : wherefore the activities of the mind follow
solely from adequate ideas, and accordingly the mind is only
passive in so far as it has inadequate ideas. Q.E.D.
Note.-Thus we see, that passive states are not attributed to
the mind, except in so far as it contains something involving
negation, or in so far as it is regarded as a part of nature,
which cannot be clearly and distinctly perceived through itself
without other parts : I could thus show, that passive states are
attributed to individual things in the same way that they are
attributed to the mind, and that they cannot otherwise be
perceived, but my purpose is solely to treat of the human mind.
PROP. IV. Nothing can be destroyed, except by a cause external
Proof.-This proposition is self-evident, for the definition
of anything affirms the essence of that thing, but does not
negative it ; in other words, it postulates the essence of the
thing, but does not take it away. So long therefore as we regard
only the thing itself, without taking into account external
causes, we shall not be able to find in it anything which could
destroy it. Q.E.D.
PROP. V. Things are naturally contrary, that is, cannot exist in
the same object, in so far as one is capable of destroying the
Proof.-If they could agree together or co-exist in the same
object, there would then be in the said object something which
could destroy it ; but this, by the foregoing proposition, is
absurd, therefore things, &c. Q.E.D.
PROP. VI. Everything, in so far as it is in itself, endeavours
to persist in its own being.
Proof.-Individual things are modes whereby the attributes of
God are expressed in a given determinate manner (I. xxv. Coroll.)
; that is, (I. xxxiv.), they are things which express in a given
determinate manner the power of God, whereby God is and acts ;
now no thing contains in itself anything whereby it can be
destroyed, or which can take away its existence (III. iv.) ; but
contrariwise it is opposed to all that could take away its
existence (III. v.). Therefore, in so far as it can, and in so
far as it is in itself, it endeavours to persist in its own
PROP. VII. The endeavour, wherewith everything endeavours to
persist in its own being, is nothing else but the actual essence
of the thing in question.
Proof.-From the given essence of any thing certain
consequences necessarily follow (I. xxxvi.), nor have things any
power save such as necessarily follows from their nature as
determined (I. xxix.) ; wherefore the power of any given thing,
or the endeavour whereby, either alone or with other things, it
acts, or endeavours to act, that is (III. vi.), the power or
endeavour, wherewith it endeavours to persist in its own being,
is nothing else but the given or actual essence of the thing in
PROP. VIII. The endeavour, whereby a thing endeavours to persist
in its own being, involves no finite time, but an indefinite
Proof.-If it involved a limited time, which should determine
the duration of the thing, it would then follow solely from that
power whereby the thing exists, that the thing could not exist
beyond the limits of that time, but that it must be destroyed ;
but this (III. iv.) is absurd. Wherefore the endeavour wherewith
a thing exists involves no definite time ; but, contrariwise,
since (III. iv.) it will by the same power whereby it already
exists always continue to exist, unless it be destroyed by some
external cause, this endeavour involves an indefinite time.
PROP. IX. The mind, both in so far as it has clear and distinct
ideas, and also in so far as it has confused ideas, endeavours to
persist in its being for an indefinite period, and of this
endeavour it is conscious.
Proof.-The essence of the mind is constituted by adequate and
inadequate ideas (III. iii.), therefore (III. vii.), both in so
far as it possesses the former, and in so far as it possesses the
latter, it endeavours to persist in its own being, and that for
an indefinite time (III. viii.). Now as the mind (II. xxiii.) is
necessarily conscious of itself through the ideas of the
modifications of the body, the mind is therefore (III. vii.)
conscious of its own endeavour.
Note.-This endeavour, when referred solely to the mind, is
called will, when referred to the mind and body in conjunction it
is called appetite ; it is, in fact, nothing else but man's
essence, from the nature of which necessarily follow all those
results which tend to its preservation ; and which man has thus
been determined to perform.
Further, between appetite and desire there is no difference,
except that the term desire is generally applied to men, in so
far as they are conscious of their appetite, and may accordingly
be thus defined : Desire is appetite with consciousness thereof.
It is thus plain from what has been said, that in no case do we
strive for, wish for, long for, or desire anything, because we
deem it to be good, but on the other hand we deem a thing to be
good, because we strive for it, wish for it, long for it, or
PROP. X. An idea, which excludes the existence of our body,
cannot be postulated in our mind, but is contrary thereto.
Proof.-Whatsoever can destroy our body, cannot be postulated
therein (III. v.). Therefore neither can the idea of such a
thing occur in God, in so far as he has the idea of our body (II.
ix. Coroll.) ; that is (II.xi., xiii.), the idea of that thing
cannot be postulated as in our mind, but contrariwise, since (II.
xi., xiii.) the first element, that constitutes the essence of
the mind, is the idea of the human body as actually existing, it
follows that the first and chief endeavour of our mind is the
endeavour to affirm the existence of our body : thus, an idea,
which negatives the existence of our body, is contrary to our
mind, &c. Q.E.D.
PROP. XI. Whatsoever increases or diminishes, helps or hinders
the power of activity in our body, the idea thereof increases or
diminishes, helps or hinders the power of thought in our mind.
Proof.-This proposition is evident from II. vii. or from II.
Note.-Thus we see, that the mind can undergo many changes,
and can pass sometimes to a state of greater perfection,
sometimes to a state of lesser perfection. These passive states
of transition explain to us the emotions of pleasure and pain.
By pleasure therefore in the following propositions I shall
signify a passive state wherein the mind passes to a greater
perfection. By pain I shall signify a passive state wherein the
mind passes to a lesser perfection. Further, the emotion of
pleasure in reference to the body and mind together I shall call
stimulation (titillatio) or merriment (hilaritas), the emotion of
pain in the same relation I shall call suffering or melancholy.
But we must bear in mind, that stimulation and suffering are
attributed to man, when one part of his nature is more affected
than the rest, merriment and melancholy, when all parts are alike
affected. What I mean by desire I have explained in the note to
Prop. ix. of this part ; beyond these three I recognize no other
primary emotion ; I will show as I proceed, that all other
emotions arise from these three. But, before I go further, I
should like here to explain at greater length Prop. x of this
part, in order that we may clearly understand how one idea is
contrary to another. In the note to II. xvii. we showed that the
idea, which constitutes the essence of mind, involves the
existence of body, so long as the body itself exists. Again, it
follows from what we pointed out in the Corollary to II. viii.,
that the present existence of our mind depends solely on the
fact, that the mind involves the actual existence of the body.
Lastly, we showed (II. xvii., xviii. and note) that the power of
the mind, whereby it imagines and remembers things, also depends
on the fact, that it involves the actual existence of the body.
Whence it follows, that the present existence of the mind and its
power of imagining are removed, as soon as the mind ceases to
affirm the present existence of the body. Now the cause, why the
mind ceases to affirm this existence of the body, cannot be the
mind itself (III. iv.), nor again the fact that the body ceases
to exist. For (by II. vi.) the cause, why the mind affirms the
existence of the body, is not that the body began to exist ;
therefore, for the same reason, it does not cease to affirm the
existence of the body, because the body ceases to exist ; but
(II. xvii.) this result follows from another idea, which excludes
the present existence of our body and, consequently, of our mind,
and which is therefore contrary to the idea constituting the
essence of our mind.
PROP. XII. The mind, as far as it can, endeavours to conceive
those things, which increase or help the power of activity in the
Proof.-So long as the human body is affected in a mode, which
involves the nature of any external body, the human mind will
regard that external body as present (II. xvii.), and
consequently (II. vii.), so long as the human mind regards an
external body as present, that is (II. xvii. note), conceives it,
the human body is affected in a mode, which involves the nature
of the said external body ; thus so long as the mind conceives
things, which increase or help the power of activity in our body,
the body is affected in modes which increase or help its power of
activity (III. Post. i.) ; consequently (III. xi.) the mind's
power of thinking is for that period increased or helped. Thus
(III. vi., ix.) the mind, as far as it can, endeavours to imagine
such things. Q.E.D.
PROP. XIII. When the mind conceives things which diminish or
hinder the body's power of activity, it endeavours, as far as
possible, to remember things which exclude the existence of the
Proof.-So long as the mind conceives anything of the kind
alluded to, the power of the mind and body is diminished or
constrained (cf. III. xii. Proof) ; nevertheless it will continue
to conceive it, until the mind conceives something else, which
excludes the present existence thereof (II. xvii.) ; that is (as
I have just shown), the power of the mind and of the body is
diminished, or constrained, until the mind conceives something
else, which excludes the existence of the former thing conceived
: therefore the mind (III. ix.), as far as it can, will endeavour
to conceive or remember the latter. Q.E.D.
Corollary.-Hence it follows that the mind shrinks from
conceiving those things, which diminish or constrain the power of
itself and of the body.
Note.-From what has been said we may clearly understand the
nature of Love and Hate. Love is nothing else but pleasure
accompanied by the idea of an external cause : Hate is nothing
else but pain accompanied by the idea of an external cause. We
further see, that he who loves necessarily endeavours to have,
and to keep present to him, the object of his love ; while he who
hates endeavours to remove and destroy the object of his hatred.
But I will treat of these matters at more length hereafter.
PROP. XIV. If the mind has once been affected by two emotions at
the same time, it will, whenever it is afterwards affected by one
of these two, be also affected by the other.
Proof.-If the human body has once been affected by two bodies
at once, whenever afterwards the mind conceives one of them, it
will straightway remember the other also (II. xviii.). But the
mind's conceptions indicate rather the emotions of our body than
the nature of external bodies (II. xvi. Coroll. ii.) ; therefore,
if the body, and consequently the mind (III. Def. iii.) has been
once affected by two emotions at the same time, it will, whenever
it is afterwards affected by one of the two, be also affected by
PROP. XV. Anything can, accidentally, be the cause of pleasure,
pain, or desire.
Proof.-Let it be granted that the mind is simultaneously
affected by two emotions, of which one neither increases nor
diminishes its power of activity, and the other does either
increase or diminish the said power (III. Post. i.). From the
foregoing proposition it is evident that, whenever the mind is
afterwards affected by the former, through its true cause, which
(by hypothesis) neither increases nor diminishes its power of
action, it will be at the same time affected by the latter, which
does increase or diminish its power of activity, that is (III.
xi. note) it will be affected with pleasure or pain. Thus the
former of the two emotions will, not through itself, but
accidentally, be the cause of pleasure or pain. In the same way
also it can be easily shown, that a thing may be accidentally the
cause of desire. Q.E.D.
Corollary.-Simply from the fact that we have regarded a thing
with the emotion of pleasure or pain, though that thing be not
the efficient cause of the emotion, we can either love or hate
Proof.-For from this fact alone it arises (III. xiv.), that
the mind afterwards conceiving the said thing is affected with
the emotion of pleasure or pain, that is (III. xi. note),
according as the power of the mind and body may be increased or
diminished, &c. ; and consequently (III. xii.), according as the
mind may desire or shrink from the conception of it (III. xiii.
Coroll.), in other words (III. xiii. note), according as it may
love or hate the same. Q.E.D.
Note.-Hence we understand how it may happen, that we love or
hate a thing without any cause for our emotion being known to us
; merely, as a phrase is, from sympathy or antipathy. We should
refer to the same category those objects, which affect us
pleasurably or painfully, simply because they resemble other
objects which affect us in the same way. This I will show in the
next Prop. I am aware that certain authors, who were the first
to introduce these terms "sympathy" and "antipathy," wished to
signify thereby some occult qualities in things ; nevertheless I
think we may be permitted to use the same terms to indicate known
or manifest qualities.
PROP. XVI. Simply from the fact that we conceive, that a given
object has some point of resemblance with another object which is
wont to affect the mind pleasurably or painfully, although the
point of resemblance be not the efficient cause of the said
emotions, we shall still regard the first-named object with love
Proof.-The point of resemblance was in the object (by
hypothesis), when we regarded it with pleasure or pain, thus
(III. xiv.), when the mind is affected by the image thereof, it
will straightway be affected by one or the other emotion, and
consequently the thing, which we perceive to have the same point
of resemblance, will be accidentally (III. xv.) a cause of
pleasure or pain. Thus (by the foregoing Corollary), although
the point in which the two objects resemble one another be not
the efficient cause of the emotion, we shall still regard the
first-named object with love or hate. Q.E.D.
PROP. XVII. If we conceive that a thing, which is wont to affect
us painfully, has any point of resemblance with another thing
which is wont to affect us with an equally strong emotion of
pleasure, we shall hate the first-named thing, and at the same
time we shall love it.
Proof.-The given thing is (by hypothesis) in itself a cause
of pain, and (III. xiii. note), in so far as we imagine it with
this emotion, we shall hate it : further, inasmuch as we conceive
that it has some point of resemblance to something else, which is
wont to affect us with an equally strong emotion of pleasure, we
shall with an equally strong impulse of pleasure love it
(III.xvi.) ; thus we shall both hate and love the same thing.
Note.-This disposition of the mind, which arises from two
contrary emotions, is called vacillation ; it stands to the
emotions in the same relation as doubt does to the imagination
(II. xliv. note) ; vacillation and doubt do not differ one from
the other, except as greater differs from less. But we must bear
in mind that I have deduced this vacillation from causes, which
give rise through themselves to one of the emotions, and to the
other accidentally. I have done this, in order that they might
be more easily deduced from what went before ; but I do not deny
that vacillation of the disposition generally arises from an
object, which is the efficient cause of both emotions. The human
body is composed (II. Post. i.) of a variety of individual parts
of different nature, and may therefore (Ax.i. after Lemma iii.
after II. xiii.) be affected in a variety of different ways by
one and the same body ; and contrariwise, as one and the same
thing can be affected in many ways, it can also in many different
ways affect one and the same part of the body. Hence we can
easily conceive, that one and the same object may be the cause of
many and conflicting emotions.
PROP. XVIII. A man is as much affected pleasurably or painfully
by the image of a thing past or future as by the image of a thing
Proof.-So long as a man is affected by the image of anything,
he will regard that thing as present, even though it be
non-existent (II. xvii. and Coroll.), he will not conceive it as
past or future, except in so far as its image is joined to the
image of time past or future (II. xliv. note). Wherefore the
image of a thing, regarded in itself alone, is identical, whether
it be referred to time past, time future, or time present ; that
is (II. xvi. Coroll.), the disposition or emotion of the body is
identical, whether the image be of a thing past, future, or
present. Thus the emotion of pleasure or pain is the ssame,
whether the image be of a thing past or future. Q.E.D.
Note I.-I call a thing past or future, according as we either
have been or shall be affected thereby. For instance, according
as we have seen it, or are about to see it, according as it has
recreated us, or will recreate us, according as it has harmed us,
or will harm us. For, as we thus conceive it, we affirm its
existence ; that is, the body is affected by no emotion which
excludes the existence of the thing, and therefore (II. xvii.)
the body is affected by the image of the thing, in the same way
as if the thing were actually present. However, as it generally
happens that those, who have had many experiences, vacillate, so
long as they regard a thing as future or past, and are usually in
doubt about its issue (II. xliv. note) ; it follows that the
emotions which arise from similar images of things are not so
constant, but are generally disturbed by the images of other
things, until men become assured of the issue.
Note II.-From what has just been said, we understand what is
meant by the terms Hope, Fear, Confidence, Despair, Joy, and
Disappointment.5 Hope is nothing else but an inconstant
pleasure, arising from the image of something future or past,
whereof we do not yet know the issue. Fear, on the other hand,
is an inconstant pain also arising from the image of something
concerning which we are in doubt. If the element of doubt be
removed from these emotions, hope becomes Confidence and fear
becomes Despair. In other words, Pleasure or Pain arising from
the image of something concerning which we have hoped or feared.
Again, Joy is Pleasure arising from the image of something past
whereof we have doubted the issue. Disappointment is the Pain
opposed to Joy.
PROP. XIX. He who conceives that the object of his love is
destroyed will feel pain ; if he conceives that it is preserved
he will feel pleasure.
Proof.-The mind, as far as possible, endeavours to conceive
those things which increase or help the body's power of activity
(III. xii.) ; in other words (III. xii. note), those things which
it loves. But conception is helped by those things which
postulate the existence of a thing, and contrariwise is hindered
by those which exclude the existence of a thing (II. xvii.) ;
therefore the images of things, which postulate the existence of
an object of love, help the mind's endeavour to conceive the
object of love, in other words (III. xi. note), affect the mind
pleasurably ; contrariwise those things, which exclude the
existence of an object of love, hinder the aforesaid mental
endeavour ; in other words, affect the mind painfully. He,
therefore, who conceives that the object of his love is destroyed
will feel pain, &c. Q.E.D.
PROP. XX. He who conceives that the object of his hate is
destroyed will also feel pleasure.
Proof.-The mind (III. xiii.) endeavours to conceive those
things, which exclude the existence of things whereby the body's
power of activity is diminished or constrained ; that is (III.
xiii. note), it endeavours to conceive such things as exclude the
existence of what it hates ; therefore the image of a thing,
which excludes the existence of what the mind hates, helps the
aforesaid mental effort, in other words (III. xi. note), affects
the mind pleasurably. Thus he who conceives that the object of
his hate is destroyed will feel pleasure. Q.E.D.
PROP. XXI. He who conceives, that the object of his love is
affected pleasurably or painfully, will himself be affected
pleasurably or painfully ; and the one or the other emotion will
be greater or less in the lover according as it is greater or
less in the thing loved.
Proof.-The images of things (as we showed in III. xix.) which
postulate the existence of the object of love, help the mind's
endeavour to conceive the said object. But pleasure postulates
the existence of something feeling pleasure, so much the more in
proportion as the emotion of pleasure is greater ; for it is
(III. xi. note) a transition to a greater perfection ; therefore
the image of pleasure in the object of love helps the mental
endeavour of the lover ; that is, it affects the lover
pleasurably, and so much the more, in proportion as this emotion
may have been greater in the object of love. This was our first
point. Further, in so far as a thing is affected with pain, it
is to that extent destroyed, the extent being in proportion to
the amount of pain (III. xi. note) ; therefore (III. xix.) he who
conceives, that the object of his love is affected painfully,
will himself be affected painfully, in proportion as the said
emotion is greater or less in the object of love. Q.E.D.
PROP. XXII. If we conceive that anything pleasurably affects
some object of our love, we shall be affected with love towards
that thing. Contrariwise, if we conceive that it affects an
object of our love painfully, we shall be affected with hatred
Proof.-He, who affects pleasurably or painfully the object of
our love, affects us also pleasurably or painfully-that is, if we
conceive the loved object as affected with the said pleasure or
pain (III. xxi.). But this pleasure or pain is postulated to come
to us accompanied by the idea of an external cause ; therefore
(III. xiii. note), if we conceive that anyone affects an object
of our love pleasurably or painfully, we shall be affected with
love or hatred towards him. Q.E.D.
Note.-Prop. xxi. explains to us the nature of Pity, which we
may define as pain arising from another's hurt. What term we can
use for pleasure arising from another's gain, I know not.
We will call the love towards him who confers a benefit on
another, Approval ; and the hatred towards him who injures
another, we will call Indignation. We must further remark, that
we not only feel pity for a thing which we have loved (as shown
in III. xxi.), but also for a thing which we have hitherto
regarded without emotion, provided that we deem that it resembles
ourselves (as I will show presently). Thus, we bestow approval
on one who has benefited anything resembling ourselves, and,
contrariwise, are indignant with him who has done it an injury.
PROP. XXIII. He who conceives, that an object of his hatred is
painfully affected, will feel pleasure. Contrariwise, if he
thinks that the said object is pleasurably affected, he will feel
pain. Each of these emotions will be greater or less, according
as its contrary is greater or less in the object of hatred.
Proof.-In so far as an object of hatred is painfully