Thought and now under the attribute of Extension. Therefore, the idea of the mind and
the mind itself are one and the same thing, conceived under one and the same attribute,
namely, Thought. The idea of the mind, I repeat, and the mind itself follow in God by
the same necessity and from the same power of thought. For in fact the idea of the
mind—that is, the idea of an idea—is nothing other than the form [forma] of the idea
insofar as the idea is considered as a mode of thinking without relation to its object. For
as soon as anyone knows something, by that very fact he knows that he knows, and at
the same time he knows that he knows that he knows, and so on ad infinitum. But I will
deal with this subject later.
PROPOSITION 22:The human mind perceives not only the affections of the body but
also the ideas of these affections.
Proof: The ideas of ideas of affections follow in God and are related to God in the
same way as ideas of affections, which can be proved in the same manner as Pr. 20, II.
But the ideas of affections of the body are in the human mind (Pr. 12, II); that is (Cor.
Pr. 11, II), in God insofar as he constitutes the essence of the human mind. Therefore,
the ideas of these ideas will be in God insofar as he has knowledge or the idea of the
human mind; that is (Pr. 21, II), they will be in the human mind itself, which therefore
perceives not only the affections of the body but also the ideas of these affections.
PROPOSITION 23:The mind does not know itself except insofar as it perceives ideas
of affections of the body.
Proof: The idea or knowledge of the mind (Pr. 20, II) follows in God and is related to
God in the same way as the idea or knowledge of the body. But since (Pr. l9, II) the human
mind does not know the human body—that is (Cor. Pr. 11, II), since the knowledge of the
human body is not related to God insofar as he constitutes the nature of the human mind—
therefore, neither is knowledge of the mind related to God insofar as he constitutes the
essence of the human mind. And so (Cor. Pr. 11, II) the human mind to that extent does not
know itself. Again, the ideas of the affections by which the body is affected involve the
nature of the human body (Pr. 16, II); that is (Pr. 13, II), they are in agreement [conveniunt]
with the nature of the mind. Therefore, the knowledge of these ideas will necessarily
involve knowledge of the mind. But (preceding Pr.) the knowledge of these ideas is in the
human mind. Therefore, the human mind knows itself but only to that extent.
PROPOSITION 24:The human mind does not involve an adequate knowledge of the
component parts of the human body.
Proof: The component parts of the human body do not pertain to the essence of
the body itself save insofar as they preserve an unvarying relation of motion with one
another (Def. after Cor. Lemma 3), and not insofar as they can be considered as indi-
vidual things apart from their relation to the human body. For the parts of the human
body (Post. 1) are very composite individual things, whose parts can be separated
from the human body (Lemma 4) without impairing in any way its nature and specific
reality [forma], and can establish a quite different relation of motion with other bodies
(Ax. 1 after Lemma 3). Therefore (Pr. 3, II), the idea or knowledge of any component
part will be in God, and will be so (Pr. 9, II) insofar as he is considered as affected by
another idea of a particular thing, a particular thing which is prior in Nature’s order to
the part itself (Pr. 7, II). Further, the same holds good of any part of an individual com-
ponent part of the human body, and so of any component part of the human body there
is knowledge in God insofar as he is affected by very many ideas of things, and not