He then attempts to define pleasure. It is something perfect and complete in itself, at each successive moment of time; hence it is not motion, which is at every moment incomplete. Pleasure is like the act of vision, or a point, or a monad, always complete in itself. It accompanies every variety of sensible perception, intelligence, and theorizing contemplation. In each of these faculties, the act is more perfect, according as the subjective element is most perfect, and the object most grand and dignified. When the act is most perfect, the pleasure accompanying it is also the most perfect; and this pleasure puts the finishing consummation to the act. The pleasure is not a pre-existing acquirement now brought into exercise, but an accessory end implicated with the act, like the fresh look which belongs to the organism just matured. It is a sure adjunct, so long as subject and object are in good condition. But continuity of pleasure, as well as of the other exercises, is impossible. Life is itself an exercise much diversified, and each man follows the diversity that is suitable to his own inclination--music, study, &c. Each has its accessory and consummating mode of pleasure; and to say that all men desire pleasure, is the same as saying that all men desire life. It is no real question to ask--Do we choose life for the sake of pleasure, or pleasure for the sake of life? The truth is, that the two are implicated and inseparable (IV.). As our acts or exercises differ from each other specifically, so also the pleasures that are accessory to them differ specifically. Exercises intellectual differ from exercises perceptive, and under each head there are varieties differing from each other. The pleasures accessory and consummating to each, are diversified accordingly. Each pleasure contributes to invigorate and intensify the particular exercise that it is attached to; the geometer who studies his science with pleasure becomes more acute and successful in prosecuting it. On the other hand, the pleasures attached to one exercise impede the mind in regard to other exercises; thus men fond of the flute cannot listen to a speaker with attention, if any one is playing the flute near them. What we delight in doing, we are more likely to do well; what we feel pain in doing, we are not likely to do well. And thus each variety of exercise is alike impeded by the pains attached to itself, and by the pleasures attached to other varieties.