the human mind (II. xii.), 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 (II. xxi.), 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.

PROP. XXIII. The mind does not know itself, except in so far as
it perceives the ideas of the modifications of the body.

Proof.--The idea or knowledge of the mind (II. xx.) follows in
God in the same manner, and is referred to God in the same
manner, as the idea or knowledge of the body. But since (II.
xix.) the human mind does not know the human body itself, that is
(II. xi. Coroll.), since the knowledge of the human body is not
referred to God, in so far as he constitutes the nature of the
human mind; therefore, neither is the knowledge of the mind
referred to God, in so far as he constitutes the essence of the
human mind; therefore (by the same Coroll. II. xi.), the human
mind thus far has no knowledge of itself. Further the ideas of
the modifications, whereby the body is affected, involve the
nature of the human body itself (II. xvi.), that is (II. xiii.),
they agree with the nature of the mind; 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.

PROP. XXIV. The human mind does not involve an adequate
knowledge of the parts composing the human body.

Proof.--The parts composing the human body do not belong to
the essence of that body, except in so far as they communicate
their motions to one another in a certain fixed relation (Def.
after Lemma iii.), not in so far as they can be regarded as
individuals without relation to the human body. The parts of the
human body are highly complex individuals (Post. i.), whose
parts (Lemma iv.) can be separated from the human body without in
any way destroying the nature and distinctive quality of the
latter, and they can communicate their motions (Ax. i., after
Lemma iii.) to other bodies in another relation; therefore (II.
iii.) the idea or knowledge of each part will be in God,
inasmuch (II. ix.) as he is regarded as affected by another idea
of a particular thing, which particular thing is prior