So, if we are going to save our initial argument whereby our guardians, set apart from all the other artificers, should be artificers of the freedom of the city, in the strictest sense, and engage in no other pursuit that does not lead in this direction, then it is necessary that they neither enact nor imitate anything else. And if they are to imitate anything, they should, from their earliest childhood, imitate only what is appropriate to these artificers of freedom; men who are courageous, sound-minded, pious, free, and everything of this sort. But they will not enact, nor be clever at imitating, anything devoid of freedom, nor anything else that is shameful, in case they proceed from enjoying the imitation, to enjoying the reality. Or haven’t you noticed, that imitations that are continued from our earliest years and beyond, become established as habits and as nature, at the level of body, speech, and indeed, of thought?

Republic IV, 395b-395d

(translation: David Horan)