dge 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 (II. xxiii.). It only perceives its own
body (II. xix.) 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 (II. xxix.), nor of its own body (II.
xxvii.), nor of external bodies (II. xxv.), but only a
fragmentary and confused knowledge thereof (II. xxviii. and
note). Q.E.D.

Note.--I say expressly, that 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.

PROP. XXX. 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 (II. Ax. i.), nor on the absolute nature of God (I.
xxi.). But (I. xxviii.) 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. (II. ix. 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 (II. xi. Coroll.), this
knowledge is very inadequate to our mind. Q.E.D.

PROP. XXXI. We can only have a very inadequate knowledge of the
duration of particular things external to ourselves.

Proof.--Every particular thing, like the human body, must be
conditioned by another particular thing to exist and operate