The passions do not really belong to the soul, but to the living body,
which is the common part, or the fusion (of both, or the compound).
The body and soul, each taken separately, are self-sufficient. Isolated
and inanimate, the body does not suffer. It is not the body that is
dissolved, it is the unification of its parts. Isolated, the soul is
impassible, indivisible, and by her condition escapes all affections.
But the unification of two things is sure to be more or less unstable,
and on its occurrence, it often happens that it is tested; hence the
pain. I say, "two things," not indeed two bodies, because two bodies
have the same nature; the present is a case where one kind of being
is to be united to one of a different kind, where the inferior being
receives something from the superior being, but receives only a trace
of that something, because of its inability to receive her entirely.
Then the whole comprises two elements, but nevertheless forms only a
unity; which, becoming something intermediary between what it was, and
what it has not been able to become, becomes seriously embarrassed,
because it has formed an unfortunate alliance, not very solid, always
drawn into opposite directions by contrary influences. Thus it is at
one time elated, and at another, dejected; when it is dejected, it
manifests its suffering; when it is elated, it aspires to communion
between the body and the soul.