passion, is easily converted into it. Hence every thing, that
is new, is most affecting, and gives us either more pleasure or pain,
than what, strictly speaking, naturally belongs to it. When it often
returns upon us, the novelty wears off; the passions subside; the
hurry of the spirits is over; and we survey the objects with greater
tranquillity.

By degrees the repetition produces a facility of the human mind, and
an infallible source of pleasure, where the facility goes not beyond
a certain degree. And here it is remarkable that the pleasure, which
arises from a moderate facility, has not the same tendency with that
which arises from novelty, to augment the painful, as well as the
agreeable affections. The pleasure of facility does not so much consist
in any ferment of the spirits, as in their orderly motion; which will
sometimes be so powerful as even to convert pain into pleasure, and give
us a relish in time what at first was most harsh and disagreeable.

But again, as facility converts pain into pleasure, so it often converts
pleasure into pain, when it is too great, and renders the actions of the
mind so faint and languid, that they are no longer able to interest and
support it. And indeed, scarce any other objects become disagreeable
through custom; but such as are naturally attended with some emotion or
affection, which is destroyed by the too frequent repetition. One
can consider the clouds, and heavens, and trees, and stones, however
frequently repeated, without ever feeling any aversion. But when the
fair sex, or music, or good cheer, or any thing, that naturally ought
to be agreeable, becomes indifferent, it easily produces the opposite
affection.

But custom not only gives a facility to perform any action, but likewise
an inclination and tendency towards it, where it is not entirely
disagreeable, and can never be the object of inclination. And this
is the reason why custom encreases all active habits, but diminishes
passive, according to the observation of a late eminent philosopher. The
facility takes off from the force of the passive habits by rendering
the motion of the spirits faint and languid. But as in the active, the
spirits are sufficiently supported of themselves, the tendency of the
mind gives them new force, and bends them more strongly to the action.

SECT. VI OF THE INFLUENCE OF THE IMAGINATION ON THE PASSIONS

It is remarkable, that the imagination and affections have close uni