On seeing certain wealthy foreigners in Rome carrying puppies and young monkeys about in their bosoms and fondling them, Caesar asked, we are told, if the women in their country did not bear children, thus in right princely fashion rebuking those who squander on animals that proneness to love and loving affection which is ours by nature, and which is due only to our fellow-men. Since, then, our souls are by nature possessed of great fondness for learning and fondness for seeing, it is surely reasonable to chide those who abuse this fondness on objects all unworthy either of their eyes or ears, to the neglect of those which are good and serviceable. Our outward sense, since it apprehends the objects which encounter it by virtue of their mere impact upon it, must needs, perhaps, regard everything that presents itself, be it useful or useless; 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 colour 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.
Plutarch, Life of Pericles