This may be shown also from the intimate connection subsisting between each Pleasure and the Working which it perfects: I mean, that the Pleasure proper to any Working increases that Working; for they who work with Pleasure sift all things more closely and carry them out to a greater degree of nicety; for instance, those men become geometricians who take Pleasure in geometry, and they apprehend particular points more completely: in like manner men who are fond of music, or architecture, or anything else, improve each on his own pursuit, because they feel Pleasure in them. Thus the Pleasures aid in increasing the Workings, and things which do so aid are proper and peculiar: but the things which are proper and peculiar to others specifically different are themselves also specifically different.
Yet even more clearly may this be shown from the fact that the Pleasures arising from one kind of Workings hinder other Workings; for instance, people who are fond of flute-music cannot keep their attention to conversation or discourse when they catch the sound of a flute; because they take more Pleasure in flute-playing than in the Working they are at the time engaged on; in other words, the Pleasure attendant on flute-playing destroys the Working of conversation or discourse.
Much the same kind of thing takes place in other cases, when a person is engaged in two different Workings at the same time: that is, the pleasanter of the two keeps pushing out the other, and, if the disparity in pleasantness be great, then more and more till a man even ceases altogether to work at the other.
This is the reason why, when we are very much pleased with anything whatever, we do nothing else, and it is only when we are but moderately pleased with one occupation that we vary it with another: people, for instance, who eat sweetmeats in the theatre do so most when the performance is indifferent.