d on contrariety of
movements or changes. Now there is a twofold contrariety in changes
and movements, as stated in _Phys._ v, 5. One is according to
approach and withdrawal in respect of the same term: and this
contrariety belongs properly to changes, i.e. to generation, which is
a change _to being,_ and to corruption, which is a change _from
being._ The other contrariety is according to opposition of termini,
and belongs properly to movements: thus whitening, which is movement
from black to white, is contrary to blackening, which is movement
from white to black.

Accordingly there is a twofold contrariety in the passions of the
soul: one, according to contrariety of objects, i.e. of good and
evil; the other, according to approach and withdrawal in respect of
the same term. In the concupiscible passions the former contrariety
alone is to be found; viz. that which is based on the objects:
whereas in the irascible passions, we find both forms of contrariety.
The reason of this is that the object of the concupiscible faculty,
as stated above (A. 1), is sensible good or evil considered
absolutely. Now good, as such, cannot be a term wherefrom, but only a
term whereto, since nothing shuns good as such; on the contrary, all
things desire it. In like manner, nothing desires evil, as such; but
all things shun it: wherefore evil cannot have the aspect of a term
whereto, but only of a term wherefrom. Accordingly every
concupiscible passion in respect of good, tends to it, as love,
desire and joy; while every concupiscible passion in respect of evil,
tends from it, as hatred, avoidance or dislike, and sorrow.
Wherefore, in the concupiscible passions, there can be no contrariety
of approach and withdrawal in respect of the same object.

On the other hand, the object of the irascible faculty is sensible
good or evil, considered not absolutely, but under the aspect of
difficulty or arduousness. Now the good which is difficult or
arduous, considered as good, is of such a nature as to produce in us
a tendency to it, which tendency pertains to the passion of _hope;_
whereas, considered as arduous or difficult, it makes us turn from
it; and this pertains to the passion of _despair._ In like manner the
arduous evil, considered as an evil, has the aspect of something to
be shunned; and this belongs to the passion of _fear:_ but it also
contains a reason for tending to it, as attempting something arduous,
whereby to escape being subject