Nicomachean Ethics

Well: human Excellence is of two kinds, Intellectual and Moral:[1] now the Intellectual springs originally, and is increased subsequently, from teaching (for the most part that is[2]), and needs therefore experience and time; whereas the Moral comes from custom, and so the Greek term denoting it is but a slight deflection from the term denoting custom in that language.

From this fact it is plain that not one of the Moral Virtues comes to be in us merely by nature: because of such things as exist by nature, none can be changed by custom: a stone, for instance, by nature gravitating downwards, could never by custom be brought to ascend, not even if one were to try and accustom it by throwing it up ten thousand times; nor could file again be brought to descend, nor in fact could anything whose nature is in one way be brought by custom to be in another. The Virtues then come to be in us neither by nature, nor in despite of nature,[3] but we are furnished by nature with a capacity for receiving themu and are perfected in them through custom.

Again, in whatever cases we get things by nature, we get the faculties first and perform the acts of working afterwards; an illustration of which is afforded by the case of our bodily senses, for it was not from having often seen or heard that we got these senses, but just the reverse: we had them and so exercised them, but did not have them because we had exercised them. But the Virtues we get by first performing single acts of working, which, again, is the case of other things, as the arts for instance; for what we have to make when we have learned how, these we learn how to make by making: men come to be builders, for instance, by building; harp-players, by playing on the harp: exactly so, by doing just actions we come to be just; by doing the actions of self-mastery we come to be perfected in self-mastery; and by doing brave actions brave.

And to the truth of this testimony is borne by what takes place in communities: because the law-givers make the individual members good men by habituation, and this is the intention certainly of every law-giver, and all who do not effect it well fail of their intent; and herein consists the difference between a good Constitution and a bad.

Again, every Virtue is either produced or destroyed from and by the very same circumstances: art too in like manner; I mean it is by playing the harp that both the good and the bad harp-players are formed: and similarly builders and all the rest; by building well men will become good builders; by doing it badly bad ones: in fact, if this had not been so, there would have been no need of instructors, but all men would have been at once good or bad in their several arts without them.

So too then is it with the Virtues: for by acting in the various relations in which we are thrown with our fellow men, we come to be, some just, some unjust: and by acting in dangerous positions and being habituated to feel fear or confidence, we come to be, some brave, others cowards.

Similarly is it also with respect to the occasions of lust and anger: for some men come to be perfected in self-mastery and mild, others destitute of all self-control and passionate; the one class by behaving in one way under them, the other by behaving in another. Or, in one word, the habits are produced from the acts of working like to them: and so what we have to do is to give a certain character to these particular acts, because the habits formed correspond to the differences of these.

So then, whether we are accustomed this way or that straight from childhood, makes not a small but an important difference, or rather I would say it makes all the difference.