How is it then that no one can feel pleasure continuously? Perhaps it is due to fatigue, since no human faculty is capable of uninterrupted activity, and therefore pleasure also is not continuous, because it accompanies the activity of the faculties. It is for the same reason that some things please us when new, but cease to give so much pleasure later; this is because at first the mind is stimulated, and acts vigorously in regard to the object, as in the case of sight when we look at something intently; but afterwards the activity is less vigorous and our attention relaxes, and consequently the pleasure also fades. [10]
It might be held that all men seek to obtain pleasure, because all men desire life. Life is a form of activity, and each man exercises his activity upon those objects and with those faculties which he likes the most: for example, the musician exercises his sense of hearing upon musical tunes, the student his intellect upon problems of philosophy, and so on. And the pleasure of these activities perfects the activities, and therefore perfects life, which all men seek. [11] Men have good reason therefore to pursue pleasure, since it perfects for each his life, which is a desirable thing. The question whether we desire life for the sake of pleasure or pleasure for the sake of life, need not be raised for the present. In any case they appear to be inseparably united; for there is no pleasure without activity, and also no perfect activity without its pleasure. 5.
This moreover is the ground for believing that pleasures vary in specific quality. For we feel that different kinds of things must have a different sort of perfection. We see this to be so with natural organisms and the productions of art, such as animals, trees, a picture, a statue, a house, a piece of furniture. Similarly we think that that which perfects one kind of activity must differ in kind from that which perfects another kind. [2] Now the activities of the intellect differ from those of the senses, and from1 one another, in kind: so also therefore do the pleasures that perfect them.
This may also be seen from the affinity which exists between the various pleasures and the activities which they perfect. For an activity is augmented by the pleasure that belongs to it; since those who work with pleasure always work with more discernment and with greater accuracy—for instance, students who are fond of geometry become proficient in it, and grasp its various problems better, and similarly lovers of music, architecture or the other arts make progress in their favorite pursuit because they enjoy it. An activity then is augmented by its pleasure; and that which augments a thing must be akin to it.