Again, the mind, both in so far as it has clear and distinct ideas, and in so far as it has confused ideas, endeavours to persist in its own being (III.

ix.); but by such an endeavour we mean desire (by the note to the same Prop.); therefore, desire is also attributable to us, in so far as we understand, or (III.

i.) in so far as we are active.

Q.E.D.
PROP.LIX.

Among all the emotions attributable to the mind as active, there are none which cannot be referred to pleasure or desire.
Proof .-- All emotions can be referred to desire, pleasure, or pain, as their definitions, already given, show.