Pericles (1.3-1.4)

but in the exercise of his mind every man, if he pleases, has the natural power to turn himself away in every case, and to change, without the least difficulty, to that object upon which he himself determines. It is meet, therefore, that he pursue what is best, to the end that he may not merely regard it, but also be edified by regarding it. A color is suited to the eye if its freshness, and its pleasantness as well, stimulates and nourishes the vision; and so our intellectual vision must be applied to such objects as, by their very charm, invite it onward to its own proper good.

Such objects are to be found in virtuous deeds; these implant in those who search them out a great and zealous eagerness which leads to imitation. In other cases, admiration of the deed is not immediately accompanied by an impulse to do it. Nay, many times, on the contrary, while we delight in the work, we despise the workman, as, for instance, in the case of perfumes and dyes; we take a delight in them, but dyers and perfumers we regard as illiberal and vulgar folk.