THE NATURE AND ORIGIN OF THE HUMAN MIND
_Introductory_
I pass on now to explain those things which must necessarily follow from
the essence of God or the Being eternal and infinite; not indeed to
explain all these things, for we have demonstrated that an infinitude of
things must follow in an infinite number of ways,--but to consider those
things only which may conduct us, as it were, by the hand to a knowledge
of the human mind and its highest happiness.
_Definitions_
I. By body, I understand a mode which expresses in a certain and
determinate manner the essence of God in so far as He is considered as
the thing extended.
II. I say that to the essence of anything pertains that, which being
given, the thing itself is necessarily posited, and being taken away,
the thing is necessarily taken; or, in other words, that, without which
the thing can neither be nor be conceived, and which in its turn cannot
be nor be conceived without the thing.
III. By idea, I understand a conception of the mind which the mind forms
because it is a thinking thing.
_Explanation._--I use the word conception rather than perception because
the name perception seems to indicate that the mind is passive in its
relation to the object. But the word conception seems to express the
action of the mind.
IV. By adequate idea, I understand an idea which, in so far as it is
considered in itself, without reference to the object, has all the
properties or internal signs (_denominationes intrinsecas_) of a true
idea.
_Explanation._--I say internal, so as to exclude that which is external,
the agreement, namely, of the idea with its object.
V. Duration is the indefinite continuation of existence.
_Explanation._--I call it indefinite because it cannot be determined by
the nature itself of the existing thing nor by the efficient cause,
which necessarily posits the existence of the thing but does not take it
away.
VI. By reality and perfection I understand the same thing.
VII. By individual things I understand things which are finite and which
have a determinate existence; and if a number of individuals so unite in
one action that they are all simultaneously the cause of one effect, I
consider them all, so far, as one individual thing.
_Axioms_
I. The essence of man does not involve necessary existence; that is to
say, the existence as well as the non-existence of this or that man may
or may not follow from the order of Nature.
II. Man thinks.
III. Modes of thought, such as love, desire, or the emotions of the
mind, by whatever name they may be called, do not exist, unless in the
same individual the idea exist of a thing loved, desired, etc. But the
idea may exist although no other mode of thinking exist.
IV. We perceive that a certain body is affected in many ways.
V. No individual things are felt or perceived by us excepting bodies and
modes of thought.
_The Mind of God_
Individual thoughts, or this and that thought, are modes which express
the nature of God in a certain and determinate manner. God therefore
possesses an attribute, the conception of which is involved in all
individual thoughts, and through which they are conceived. Thought,
therefore, is one of the infinite attributes of God which expresses the
eternal and infinite essence of God or, in other words, God is a
thinking thing.
This proposition is plain from the fact that we can conceive an infinite
thinking Being. For the more things a thinking being can think, the more
reality or perfection we conceive it to possess, and therefore the being
which can think an infinitude of things in infinite ways is necessarily
infinite by his power of thinking. Since, therefore, we can conceive an
infinite Being by attending to thought alone, thought is necessarily one
of the infinite attributes of God.[14]
God can think an infinitude of things in infinite ways, or (which is the
same thing) can form an idea of His essence and of all the things which
necessarily follow from it. But everything which is in the power of God
is necessary. Therefore in God there necessarily exists the idea of His
essence, and of all things which necessarily follow from His essence.
The infinite intellect comprehends nothing but the attributes of God and
His modes. But God is one. Therefore the idea of God, from which
infinite numbers of things follow in infinite ways, can be one only.
The common people understand by God's power His free will and right over
all existing things, which are therefore commonly looked upon as
contingent; for they say that God has the power of destroying everything
and reducing it to nothing. They very frequently, too, compare God's
power with the power of kings. That there is any similarity between the
two we have disproved. We have shown that God does everything with that
necessity with which He understands Himself; that is to say, as it
follows from the necessity of the divine nature that God understands
Himself (a truth admitted by all), so by the same necessity it follows
that God does an infinitude of things in infinite ways. Moreover, we
have shown that the power of God is nothing but the active essence of
God, and therefore it is as impossible for us to conceive that God does
not act as that He does not exist. If it pleased me to go farther, I
could show besides that the power which the common people ascribe to God
is not only a human power (which shows that they look upon God as a man,
or as being like a man), but that it also involves weakness. But I do
not care to talk so much upon the same subject. Again and again I ask
the reader to consider and reconsider what is said upon this subject
[above].[15] For it is not possible for any one properly to understand
the things which I wish to prove unless he takes great care not to
confound the power of God with the human power and right of kings.
_The Order and Dependence of Ideas in God_
The formal Being of ideas is a mode of thought (as is self-evident);
that is to say, a mode which expresses in a certain manner the nature of
God in so far as He is a thinking thing. It is a mode, therefore, that
involves the conception of no other attribute of God, and consequently
is the effect of no other attribute except that of thought; therefore
the formal Being of ideas recognizes God for its cause in so far only as
He is considered as a thinking thing, and not in so far as He is
manifested by any other attribute; that is to say, the ideas both of
God's attributes and of individual things do not recognize as their
efficient cause the objects of the ideas or the things which are
perceived, but God Himself in so far as He is a thinking thing.[16]
God's power of thinking is equal to His actual power of acting; that is
to say, whatever follows _formally_ from the infinite nature of God,
follows from the idea of God (idea Dei), in the same order and in the
same connection _objectively_ in God.
The order and connection of ideas is the same as the order and
connection of things.
Before we go any farther, we must here recall to our memory what we have
already demonstrated, that everything which can be perceived by the
infinite intellect as constituting the essence of substance pertains
entirely to the one sole substance only, and consequently that substance
thinking and substance extended are one and the same substance, which is
now comprehended under this attribute and now under that. Thus, also, a
mode of extension and the idea of that mode are one and the same thing
expressed in two different ways--a truth which some of the Hebrews
appear to have seen as if through a cloud, since they say that God, the
intellect of God, and the things which are the objects of that intellect
are one and the same thing. For example, the circle existing in nature
and the idea that is in God of an existing circle are one and the same
thing, which is manifested through different attributes; and, therefore,
whether we think of Nature under the attribute of extension, or under
the attribute of thought, or under any other attribute whatever, we
shall discover one and the same order, or one and the same connection of
causes; that is to say, in every case the same sequence of things. Nor
have I had any other reason for saying that God is the cause of the
idea, for example, of the circle in so far only as He is a thinking
thing, and of the circle itself in so far as He is an extended thing,
but this, that the formal Being of the idea of a circle can only be
perceived through another mode of thought, as its proximate cause, and
this again must be perceived through another, and so on _ad infinitum_.
So that when things are considered as modes of thought, we must explain
the order of the whole of Nature or the connection of causes by the
attribute of thought alone, and when things are considered as modes of
extension, the order of the whole of Nature must be explained through
the attribute of extension alone, and so with other attributes.
Therefore God is in truth the cause of things as they are in themselves
in so far as He consists of infinite attributes, nor for the present can
I explain the matter more clearly.
_The Origin of the Human Mind_
The human mind is a part of the infinite intellect of God, and
therefore, when we say that the human mind perceives this or that thing,
we say nothing else than that God has this or that idea; not indeed in
so far as He is infinite, but in so far as He is manifested through the
nature of the human mind, or in so far as He forms the essence of the
human mind; and when we say that God has this or that idea, not merely
in so far as He forms the nature of the human mind, but in so far as He
has at the same time with the human mind the idea also of another thing,
then we say that the human mind perceives the thing partially or
inadequately.
... When you ask me my opinion on the question[17] raised concerning
our knowledge of the means, whereby each part of Nature agrees with its
whole, and the manner in which it is associated with the remaining
parts, I presume you are asking for the reasons which induce us to
believe that each part of Nature agrees with its whole, and is
associated with the remaining parts. For as to the means whereby the
parts are really associated, and each part agrees with its whole, I told
you in my former letter that I am in ignorance. To answer such a
question we should have to know the whole of Nature and its several
parts. I will therefore endeavor to show the reason which led me to make
the statement; but I will promise that I do not attribute to Nature
either beauty or deformity, order or confusion. Only in relation to our
imagination can things be called beautiful or deformed, ordered or
confused.
By the association of parts, then, I merely mean that the laws or nature
of one part adapt themselves to the laws or nature of another part, so
as to cause the least possible inconsistency. As to the whole and the
parts, I mean that a given number of things are parts of a whole, in so
far as the nature of each of them is adapted to the nature of the rest
so that they all, as far as possible, agree together. On the other hand,
in so far as they do not agree, each of them forms, in our minds, a
separate idea, and is to that extent considered as a whole, not as a
part. For instance, when the parts of lymph, chyle, etc., combine,
according to the proportion of the figure and size of each, so as to
evidently unite, and form one fluid, the chyle, lymph, etc., considered
under this aspect, are part of the blood; but, in so far as we consider
the particles of lymph as differing in figure and size from the
particles of chyle, we shall consider each of the two as a whole, not as
a part.
Let us imagine, with your permission, a little worm, living in the
blood, able to distinguish by sight the particles of blood, lymph, etc.,
and to reflect on the manner in which each particle, on meeting with
another particle, either is repulsed, or communicates a portion of its
own motion. This little worm would live in the blood in the same way as
we live in a part of the universe, and would consider each particle of
blood, not as a part, but as a whole. He would be unable to determine
how all the parts are modified by the general nature of blood, and are
compelled by it to adapt themselves so as to stand in a fixed relation
to one another. For if we imagine that there are no causes external to
the blood, which could communicate fresh movements to it, nor any space
beyond the blood, nor any bodies whereto the particles of blood could
communicate their motion, it is certain that the blood would always
remain in the same state, and its particles would undergo no
modifications, save those which may be conceived as arising from the
relations of motion existing between the lymph, the chyle, etc. The
blood would then always have to be considered as a whole, not as a part.
But as there exist, as a matter of fact, very many causes which modify,
in a given manner, the nature of blood, and are, in turn, modified
thereby, it follows that other motions and other relations arise in the
blood, springing not from the mutual relations of its parts only, but
from the mutual relations between the blood as a whole and external
causes. Thus the blood comes to be regarded as a part, not as a whole.
So much for the whole and the part.
All natural bodies can and ought to be considered in the same way as we
have here considered the blood, for all bodies are surrounded by others,
and are mutually determined to exist and operate in a fixed and definite
proportion, while the relations between motion and rest in the sum total
of them, that is, in the whole universe, remain unchanged. Hence it
follows that each body, in so far as it exists as modified in a
particular manner, must be considered as a part of the whole universe,
as agreeing with the whole, and associated with the remaining parts. As
the nature of the universe is not limited, like the nature of blood, but
is absolutely infinite, its parts are by this nature of infinite power
infinitely modified, and compelled to undergo infinite variations....
You see, therefore, how and why I think that the human body is a part of
Nature. As regards the human mind, I believe that it also is a part of
Nature; for I maintain that there exists in Nature an infinite power of
thinking, which, in so far as it is infinite, contains subjectively the
whole of Nature, and its thoughts proceed in the same manner as
Nature--that is, in the sphere of ideas. Further, I take the human mind
to be identical with this said power, not in so far as it is infinite,
and perceives the whole of Nature, but in so far as it is finite, and
perceives only the human body. In this manner, I maintain that the human
mind is part of an infinite understanding.
_The Nature of the Human Mind_
The essence of man is formed by certain modes of the attributes of God,
that is to say, modes of thought, the idea of all of them being prior by
nature to the modes of thought themselves; and if this idea exists,
other modes (which also have an idea in nature prior to them) must exist
in the same individual likewise. Therefore an idea is the first thing
which forms the Being of the human mind. But it is not the idea of a
non-existent thing, for then the idea itself could not be said to exist.
It will therefore be the idea of something actually existing. Neither
will it be the idea of an infinite thing, for an infinite thing must
always necessarily exist, and this is absurd. Therefore the first thing
which forms the actual Being of the human mind is the idea of an
individual thing actually existing.
The knowledge of everything which happens in the object of any idea
necessarily exists in God, in so far as He is considered as modified by
the idea of that object; that is to say, in so far as He forms the mind
of any being. The knowledge, therefore, necessarily exists in God of
everything which happens in the object of the idea constituting the
human mind; that is to say, it exists in Him in so far as He forms the
nature of the human mind; or, whatever happens in the object of the idea
constituting the human mind must be perceived by the human mind; in
other words, an idea of that thing will necessarily exist in the human
mind. That is to say, if the object of the idea constituting the human
mind be a body, nothing can happen in that body which is not perceived
by the mind.
If the body were not the object of the human mind, the ideas of the
modifications of the body would not be in God, in so far as He has
formed our mind, but would be in Him in so far as He has formed the mind
of another thing; that is to say, the ideas of the modifications of the
body would not be in our mind. But we have ideas of the modifications of
a body; therefore the object of the idea constituting the human mind is
a body, and that, too, actually existing. Again, if there were also any
other object of the mind besides a body, since nothing exists from which
some effect does not follow, the idea of some effort produced by this
object would necessarily exist in our mind. But there is no such idea.
Therefore the object of the idea constituting the human mind is a body,
or a certain mode of extension actually existing, and nothing else.
Hence it follows that man is composed of mind and body, and that the
human body exists as we perceive it.
Hence we see not only that the human mind is united to the body, but
also what is to be understood by the union of the mind and body. But no
one can understand it adequately or distinctly without knowing
adequately beforehand the nature of our body; for those things which we
have proved hitherto are altogether general, nor do they refer more to
man than to other individuals, all of which are animate, although in
different degrees. For of everything there necessarily exists in God an
idea of which He is the cause, in the same way as the idea of the human
body exists in Him; and therefore everything that we have said of the
idea of the human body is necessarily true of the idea of any other
thing. We cannot, however, deny that ideas, like objects themselves,
differ from one another, and that one is more excellent and contains
more reality than another, just as the object of one idea is more
excellent and contains more reality than another. Therefore, in order to
determine the differences between the human mind and other things and
its superiority over them, we must first know, as we have said, the
nature of its object, that is to say, the nature of the human body. I am
not able to explain it here, nor is such an explanation necessary for
what I wish to demonstrate.
This much, nevertheless, I will say generally, that in proportion as one
body is better adapted than another to do or suffer many things, in the
same proportion will the mind at the same time be better adapted to
perceive many things, and the more the actions of a body depend upon
itself alone, and the less other bodies cooeperate with it in action, the
better adapted will the mind be for distinctly understanding. We can
thus determine the superiority of one mind to another; we can also see
the reason why we have only a very confused knowledge of our body,
together with many other things which I shall deduce in what follows.
_The Complexity of the Human Mind_
The idea which constitutes the formal Being of the human mind is the
idea of a body which is composed of a number of individuals composite to
a high degree. But an idea of each individual composing the body must
necessarily exist in God; therefore the idea of the human body is
composed of these several ideas of the component parts. The idea which
constitutes the formal Being of the human mind is not simple, but is
composed of a number of ideas.
All ways in which any body is affected follow at the same time from the
nature of the affected body, and from the nature of the affecting body;
therefore the idea of these modifications necessarily involves the
nature of each body, and therefore the idea of each way in which the
human body is affected by an external body involves the nature of the
human body and of the external body.
Hence it follows, in the first place, that the human mind perceives the
nature of many bodies together with that of its own body.
It follows, secondly, that the ideas we have of external bodies indicate
the constitution of our own body rather than the nature of external
bodies.
_Imagination_
If the human body be affected in a way which involves the nature of any
external body, the human mind will contemplate that external body as
actually existing or as present, until the human body be affected by a
mode which excludes the existence or presence of the external body.
When external bodies so determine the fluid parts of the human body that
they often strike upon the softer parts, the fluid parts change the
plane of the soft parts, and thence it happens that the fluid parts are
reflected from the new planes in a direction different from that in
which they used to be reflected, and that also afterwards when they
strike against these new planes by their own spontaneous motion, they
are reflected in the same way as when they were impelled towards those
planes by external bodies. Consequently those fluid bodies produce a
modification in the human body while they keep up this reflex motion
similar to that produced by the presence of an external body. The mind,
therefore, will think as before, that is to say, it will again
contemplate the external body as present. This will happen as often as
the fluid parts of the human body strike against those planes by their
own spontaneous motion. Therefore, although the external bodies by which
the human body was once affected do not exist the mind will perceive
them as if they were present so often as this action is repeated in the
body.
We see, therefore, how it is possible for us to contemplate things which
do not exist as if they were actually present. This may indeed be
produced by other causes, but I am satisfied with having here shown one
cause through which I could explain it, just as if I had explained it
through the true cause. I do not think, however, that I am far from the
truth, since no postulate which I have assumed contains anything which
is not confirmed by an experience that we cannot mistrust, after we have
proved the existence of the human body as we perceive it.
We clearly see, moreover, what is the difference between the idea, for
example, of Peter, which constitutes the essence of the mind itself of
Peter, and the idea of Peter himself which is in another man; for
example, in Paul. For the former directly manifests the essence of the
body of Peter himself, nor does it involve existence unless so long as
Peter exists; the latter, on the other hand, indicates rather the
constitution of the body of Paul than the nature of Peter; and therefore
so long as Paul's body exists with that constitution, so long will
Paul's mind contemplate Peter as present, although he does not exist.
But in order that we may retain the customary phraseology, we will give
to those modifications of the human body, the ideas of which represent
to us external bodies as if they were present, the name of _images of
things_, although they do not actually reproduce the forms of the
things. When the mind contemplates bodies in this way, we will say that
it imagines. Here I wish it to be observed, in order that I may begin to
show what _error_ is, that these imaginations of the mind, regarded by
themselves, contain no error, and that the mind is not in error because
it imagines, but only in so far as it is considered as wanting in an
idea which excludes the existence of those things which it imagines as
present. For if the mind, when it imagines non-existent things to be
present, could at the same time know that those things did not really
exist, it would think its power of imagination to be a virtue of its
nature and not a defect, especially if this faculty of imagining
depended upon its own nature alone, that is to say, if this faculty of
the mind were free.
_Association of Ideas and Memory_
If the human body has at any time been simultaneously affected by two or
more bodies, whenever the mind afterwards imagines one of them, it will
also remember the others.
We clearly understand by this what memory is. It is nothing else than a
certain concatenation of ideas, involving the nature of things which are
outside the human body, a concatenation which corresponds in the mind to
the order and concatenation of the modifications of the human body. I
say, firstly, that it is a concatenation of those ideas only which
involve the nature of things which are outside the human body, and not
of those ideas which explain the nature of those things, for there are
in truth ideas of the modifications of the human body, which involve its
nature as well as the nature of external bodies. I say, in the second
place, that this concatenation takes place according to the order and
concatenation of the modifications of the human body, that I may
distinguish it from the concatenation of ideas which takes place
according to the order of the intellect, and enables the mind to
perceive things through their first causes, and is the same in all men.
Hence we can clearly understand how it is that the mind from the thought
of one thing at once turns to the thought of another thing which is not
in any way like the first. For example, from the thought of the word
_pomum_ a Roman immediately turned to the thought of the fruit, which
has no resemblance to the articulate sound _pomum_, nor anything in
common with it, excepting this, that the body of that man was often
affected by the thing and the sound; that is to say, he often heard the
word _pomum_ when he saw the fruit. In this manner each person will turn
from one thought to another according to the manner in which the habit
of each has arranged the images of things in the body. The soldier, for
instance, if he sees the footsteps of a horse in the sand, will
immediately turn from the thought of a horse to the thought of a
horseman, and so to the thought of war. The countryman, on the other
hand, from the thought of a horse will turn to the thought of his plow,
his field, etc.; and thus each person will turn from one thought to this
or that thought, according to the manner in which he has been accustomed
to connect and bind together the images of things in his mind.
FOOTNOTES:
[14] [Similarly, it can be demonstrated that] extension is an attribute
of God, or God is an extended thing.
[15] Chapter Eight.
[16] The formal Being of things which are not modes of thought does not
follow from the divine nature because of His prior knowledge of these
things, but, just as ideas follow from the attribute of thought, in the
same manner and with the same necessity the objects of ideas follow and
are concluded from their attributes.
[17] From a letter to Henry Oldenburg (1665).