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.
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 coöperate 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.