The Philosophy of Spinoza

by Benedictus de Spinoza

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.