and a difficulty of the spirit's moving in their new direction. As this difficulty excites the spirits, 'tis the source of wonder, surprize, and of all the emotions, which arise from novelty; and is in itself very agreeable, like every thing, which inlivens the mind to a moderate degree. 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. 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, 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; which will sometimes be so powerful as even to convert pain into pleasure, and give us a relish in time for 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 thro' custom; but such as are naturally attended with some emotion or affection, which is destroy'd by the too frequent repetition. One can consider the clouds, and heavens, and trees, an stones, however frequently repeated, without ever
