fear and terror, when
he reflects on the enemy. Whatever new emotion, therefore, proceeds
from the former naturally encreases the courage; as the same emotion,
proceeding from the latter, augments the fear; by the relation of ideas,
and the conversion of the inferior emotion into the predominant. Hence
it is that in martial discipline, the uniformity and lustre of our
habit, the regularity of our figures and motions, with all the pomp and
majesty of war, encourage ourselves and allies; while the same objects
in the enemy strike terror into us, though agreeable and beautiful in
themselves.

Since passions, however independent, are naturally transfused into each
other, if they are both present at the same time; it follows, that when
good or evil is placed in such a situation, as to cause any particular
emotion, beside its direct passion of desire or aversion, that latter
passion must acquire new force and violence.

This happens, among other cases, whenever any object excites contrary
passions. For it is observable that an opposition of passions commonly
causes a new emotion in the spirits, and produces more disorder, than
the concurrence of any two affections of equal force. This new emotion
is easily converted into the predominant passion, and encreases its
violence, beyond the pitch it would have arrived at had it met with
no opposition. Hence we naturally desire what is forbid, and take a
pleasure in performing actions, merely because they are unlawful.
The notion of duty, when opposite to the passions, is seldom able
to overcome them; and when it fails of that effect, is apt rather to
encrease them, by producing an opposition in our motives and principles.
The same effect follows whether the opposition arises from internal
motives or external obstacles. The passion commonly acquires new force
and violence in both cases.

The efforts, which the mind makes to surmount the obstacle, excite the
spirits and inliven the passion.

Uncertainty has the same influence as opposition. The agitation of the
thought; the quick turns it makes from one view to another; the variety
of passions, which succeed each other, according to the different views;
All these produce an agitation in the mind, and transfuse themselves
into the predominant passion.

There is not in my opinion any other natural cause, why security
diminishes the passions, than because it removes that uncertainty, which
encreases them. The mind, when left to it