e thus defined: Desire is appetite with consciousness thereof.
It is thus plain from what has been said, that in no case do we
strive for, wish for, long for, or desire anything, because we
deem it to be good, but on the other hand we deem a thing to be
good, because we strive for it, wish for it, long for it, or
desire it.

PROP. X. An idea, which excludes the existence of our body,
cannot be postulated in our mind, but is contrary thereto.

Proof.--Whatsoever can destroy our body, cannot be postulated
therein (III. v.). Therefore neither can the idea of such a
thing occur in God, in so far as he has the idea of our body (II.
ix. Coroll.); that is (II. xi., xiii.), the idea of that thing
cannot be postulated as in our mind, but contrariwise, since (II.
xi., xiii.) the first element, that constitutes the essence of
the mind, is the idea of the human body as actually existing, it
follows that the first and chief endeavour of our mind is the
endeavour to affirm the existence of our body: thus, an idea,
which negatives the existence of our body, is contrary to our
mind, &c. Q.E.D.

PROP. XI. Whatsoever increases or diminishes, helps or hinders
the power of activity in our body, the idea thereof increases or
diminishes, helps or hinders the power of thought in our mind.

Proof.--This proposition is evident from II. vii. or from II.
xiv.

Note.--Thus we see, that the mind can undergo many changes,
and can pass sometimes to a state of greater perfection,
sometimes to a state of lesser perfection. These passive states
of transition explain to us the emotions of pleasure and pain.
By pleasure therefore in the following propositions I shall
signify a passive state wherein the mind passes to a greater
perfection. By pain I shall signify a passive state wherein the
mind passes to a lesser perfection. Further, the emotion of
pleasure in reference to the body and mind together I shall call
stimulation (titillatio) or merriment (hilaritas), the emotion of
pain in the same relation I shall call suffering or melancholy.
But we must bear in mind, that stimulation and suffering are
attributed to man, when one part of his nature is more affected
than the rest, merriment and melancholy, when all parts are alike
affected. What I mean by desire I have explained in the note to
Prop. ix. of this part; beyond these three I recognize no other
primary emotion; I will show as I proceed, that all other
emotions arise from these thr