David Hume

“ By degrees the repetition produces a facility, which is another very powerful principle of the human mind, and an infallible source of pleasure, where the facility goes not beyond a certain degree. And here 'tis 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 ”

“ 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 ”

“ One can consider the clouds, and heavens, and trees, an 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. ”

“ When the soul applies itself to the performance of any action, or the conception of any object, to which it is not accustom'd, there is a certain unpliableness in the faculties, and a difficulty of the spirit's moving in their new direction. ”

“ 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. ”

“ But tho' surprize be agreeable in itself, yet as it puts the spirits in agitation, it not only augments our agreeable affections, but also our painful, according to the foregoing principle, that every emotion, which precedes or attends a passion, is easily converted into it. ”