PROP. XLI.  Knowledge of the first kind is the only source of
falsity, knowledge of the second and third kinds is necessarily
true.
    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.
xxxiv.).  Q.E.D.

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
perceived.
    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 quГўdam Г¦ternitatis
specie).
    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.
Q.E.D.

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,
involves.
    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 versГў, 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
part.
    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
possible.
    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
subject.
    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
right angles.
    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.




PART III.

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
restraint.
    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
solids.


DEFINITIONS

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.


POSTULATES

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
less.
    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.
xvii.).

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.
Q.E.D.
    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
it.
    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
inadequate ideas.
    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
to itself.
    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
other.
    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
being.  Q.E.D.

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
question.  Q.E.D.