Modifications of the Human Body
Table of Contents
21. This idea of the mind is united to the mind in the same way as the mind is united to the body.
Proof: The body is the object of the mind (2.12 and 2.13). This is why it is united to the body. Q.E.D.
Note: This proposition is comprehended much more clearly from what we have said in the note to 2.7.
We there showed that the idea of body and body, that is, mind and body (2.13), are one and the same individual conceived now under the attribute of thought, now under the attribute of extension.
Wherefore the idea of the mind and the mind itself are one and the same thing, which is conceived under one and the same attribute, namely, thought.
The idea of the mind, I repeat, and the mind itself are in God by the same necessity and follow from him from the same power of thinking.
Strictly speaking, the idea of the mind, that is, the idea of an idea, is nothing but the distinctive quality (forma) of the idea in so far as it is conceived as a mode of thought without reference to the object;
If a man knows anything, he, by that very fact, knows that he knows it, and at the same time knows that he knows that he knows it, and so on to infinity.
22. The human mind perceives not only the modifications of the body, but also the ideas of such modifications.
Proof: The ideas of the ideas of modifications:
- follow in God in the same way
- are referred to God in the same way, as the ideas of the said modifications.
This is proved in the same way as 2.20.
But the ideas of the modifications of the body are in the human mind (2.12), that is, in God, in so far as he constitutes the essence of the human mind.
Therefore the ideas of these ideas will be in God, in so far as he has the knowledge or idea of the human mind, that is (2.21).
They will be in the human mind itself, which therefore perceives not only the modifications of the body, but also the ideas of such modifications. Q.E.D.
23. The mind does not know itself. It only perceives the ideas of the modifications of the body.
Proof: The knowledge of the mind (2.20) follows in God in the same way, referred to God in the same way, as the idea or knowledge of the body.
But the knowledge of the human body is not referred to God, in so far as he constitutes the nature of the human mind.
- This is why (2.19) the human mind does not know the human body itself.
Therefore, the human mind thus far has no knowledge of itself.
The ideas of the modifications affect the body.
- These involve the nature of the human body itself (2.16)
- They agree with the nature of the mind (2.13).
Wherefore, the knowledge of these ideas necessarily involves knowledge of the mind.
But (by the last Prop.) the knowledge of these ideas is in the human mind itself; wherefore the human mind thus far only has knowledge of itself. Q.E.D.
24. The human mind does not involve an adequate knowledge of the parts composing the human body.
Proof: Our body parts do not belong to the essence of our body, except in so far as they communicate their motions to one another in a certain fixed relation (Def. after Lemma 3).
They cannot be regarded as individuals unrelated to the human body.
The parts of the human body are highly complex individuals (Post. 1), whose parts (Lemma 4) can be separated from the human body without in any way destroying the nature and distinctive quality of the latter.
They can communicate their motions (Ax. 1, after Lemma 3) to other bodies in another relation.
Therefore (2.3) the idea or knowledge of each part will be in God, inasmuch (2.9) as he is regarded as affected by another idea of a particular thing, which particular thing is prior in the order of nature to the aforesaid part (2.7).
We may affirm the same thing of each part of each individual composing the human body.
Therefore, the knowledge of each part composing the human body is in God, in so far as he is affected by very many ideas of things, and not in so far as he has the idea of the human body only, in other words, the idea which constitutes the nature of the human mind (2.13).
Therefore (2.11. Coroll.), the human mind does not involve an adequate knowledge of the human body. Q.E.D. –>
25. The idea of each modification of the human body does not involve an adequate knowledge of the external body.
Proof: The idea of a modification of the human body involves the nature of an external body, in so far as that external body conditions the human body in a given manner.
But, in so far as the external body is an individual, which has no reference to the human body, the knowledge or idea thereof is in God (2.9), in so far as God is regarded as affected by the idea of a further thing, which (2.7) is naturally prior to the said external body.
Wherefore an adequate knowledge of the external body is not in God, in so far as he has the idea of the modification of the human body.
In other words, the idea of the modification of the human body does not involve an adequate knowledge of the external body. Q.E.D.
26. The human mind does not perceive any external body as actually existing, except through the ideas of the modifications of its own body.
Proof: If the human body is in no way affected by a given external body, then (2.7) neither is the idea of the human body, in other words, the human mind, affected in any way by the idea of the existence of the said external body, nor does it in any manner perceive its existence.
But, in so far as the human body is affected in any way by a given external body, thus far (2.16 and Coroll.) it perceives that external body. Q.E.D.
Corollary: In so far as the human mind imagines an external body, it has not an adequate knowledge thereof. Proof= When the human mind regards external bodies through the ideas of the modifications of its own body, we say that it imagines (see 2.17 note).
The mind can only imagine external bodies as actually existing.
Therefore (by 2.25), in so far as the mind imagines external bodies, it has not an adequate knowledge of them. Q.E.D. –>
27. The idea of each modification of the human body does not involve an adequate knowledge of the human body itself.
Proof: Every idea of a modification of the human body involves the nature of the human body, in so far as the human body is regarded as affected in a given manner (2.16).
But, inasmuch as the human body is an individual which may be affected in many other ways, the idea of the said modification, &c. Q.E.D.
28. The ideas of the modifications of the human body, in so far as they have reference only to the human mind, are not clear and distinct, but confused.
Proof: The ideas of the modifications of the human body involve the nature both of the human body and of external bodies (2.16).
They must involve the nature not only of the human body but also of its parts; for the modifications are modes (Post. 3), whereby the parts of the human body, and, consequently, the human body as a whole are affected.
But (by 2.24, 2.25) the adequate knowledge of external bodies, as also of the parts composing the human body, is not in God, in so far as he is regarded as affected by the human mind, but in so far as he is regarded as affected by other ideas.
These ideas of modifications, in so far as they are referred to the human mind alone, are as consequences without premises, in other words, confused ideas. Q.E.D.
Note: The idea which constitutes the nature of the human mind is, in the same manner, proved not to be, when considered in itself alone, clear and distinct; as also is the case with the idea of the human mind, and the ideas of the ideas of the modifications of the human body, in so far as they are referred to the mind only, as everyone may easily see. –>
29. The idea of the idea of each modification of the human body does not involve an adequate knowledge of the human mind.
Proof: The idea of a modification of the human body (2.27) does not involve an adequate knowledge of the said body, in other words, does not adequately express its nature;
That is (2.13) it does not agree with the nature of the mind adequately.
Therefore (1. Ax. 6) the idea of this idea does not adequately express the nature of the human mind, or does not involve an adequate knowledge thereof.
Corollary: Hence it follows that the human mind, when it perceives things after the common order of nature, has not an adequate but only a confused and fragmentary knowledge of itself, of its own body, and of external bodies.
For the mind does not know itself, except in so far as it perceives the ideas of the modifications of body (2.23).
It only perceives its own body (2.19) through the ideas of the modifications, and only perceives external bodies through the same means;
Thus, in so far as it has such ideas of modification, it has not an adequate knowledge of itself (2.29), nor of its own body (2.27), nor of external bodies (2.25), but only a fragmentary and confused knowledge thereof (2.28 and note). Q.E.D.
Note: The mind has not an adequate but only a confused knowledge of itself, its own body, and of external bodies, whenever it perceives things after the common order of nature.
That is, whenever it is determined from without, namely, by the fortuitous play of circumstance, to regard this or that; not at such times as it is determined from within, that is, by the fact of regarding several things at once, to understand their points of agreement, difference, and contrast.
Whenever it is determined in anywise from within, it regards things clearly and distinctly, as I will show below. –>
30. We can only have a very inadequate knowledge of the duration of our body.
Proof: The duration of our body does not depend on its essence (2. Ax. 1), nor on the absolute nature of God (1.21).
But (1.28) it is conditioned to exist and operate by causes, which in their turn are conditioned to exist and operate in a fixed and definite relation by other causes, these last again being conditioned by others, and so on to infinity.
The duration of our body therefore depends on the common order of nature, or the constitution of things.
Now, however a thing may be constituted, the adequate knowledge of that thing is in God, in so far as he has the ideas of all things, and not in so far as he has the idea of the human body only.
(2.9. Coroll.) Wherefore the knowledge of the duration of our body is in God very inadequate, in so far as he is only regarded as constituting the nature of the human mind; that is (2.11. Coroll.), this knowledge is very inadequate to our mind. Q.E.D.