in question.

Proof.--From the given essence of any thing certain
consequences necessarily follow (I. xxxvi.), nor have things any
power save such as necessarily follows from their nature as
determined (I. xxix.); wherefore the power of any given thing,
or the endeavour whereby, either alone or with other things, it
acts, or endeavours to act, that is (III. vi.), the power or
endeavour, wherewith it endeavours to persist in its own being,
is nothing else but the given or actual essence of the thing in
question. Q.E.D.

PROP. VIII. The endeavour, whereby a thing endeavours to persist
in its own being, involves no finite time, but an indefinite
time.

Proof.--If it involved a limited time, which should determine
the duration of the thing, it would then follow solely from that
power whereby the thing exists, that the thing could not exist
beyond the limits of that time, but that it must be destroyed;
but this (III. iv.) is absurd. Wherefore the endeavour wherewith
a thing exists involves no definite time; but, contrariwise,
since (III. iv.) it will by the same power whereby it already
exists always continue to exist, unless it be destroyed by some
external cause, this endeavour involves an indefinite time.

PROP. IX. The mind, both in so far as it has clear and distinct
ideas, and also in so far as it has confused ideas, endeavours to
persist in its being for an indefinite period, and of this
endeavour it is conscious.

Proof.--The essence of the mind is constituted by adequate and
inadequate ideas (III. iii.), therefore (III. vii.), both in so
far as it possesses the former, and in so far as it possesses the
latter, it endeavours to persist in its own being, and that for
an indefinite time (III. viii.). Now as the mind (II. xxiii.) is
necessarily conscious of itself through the ideas of the
modifications of the body, the mind is therefore (III. vii.)
conscious of its own endeavour.

Note.--This endeavour, when referred solely to the mind, is
called will, when referred to the mind and body in conjunction it
is called appetite; it is, in fact, nothing else but man's
essence, from the nature of which necessarily follow all those
results which tend to its preservation; and which man has thus
been determined to perform.

Further, between appetite and desire there is no difference,
except that the term desire is generally applied to men, in so
far as they are conscious of their appetite, and may accordingly
b