Moreover, the same causes and the same means that produce any excellence or virtue can also destroy it, and this is also true of every art.1 It is by playing the harp that men become both good and bad harpists, and correspondingly with builders and all the other craftsmen: a man who builds well will be a good builder, one who builds badly a bad one. For if this were not so, there would be no need for an instructor, but everybody would be born as a good or a bad craftsman. The same holds true of the virtues: in our transactions with other men it is by action that some become just and others unjust, and it is by acting in the face of danger and by developing the habit of feeling fear or confidence that some become brave men and others cowards. The same applies to the appetites and feelings of anger: by reacting in one way or in another to given circumstances some people become self-controlled and gentle, and others self-indulgent and short-tempered. In a word, characteristics2 develop from corresponding activities. For that reason, we must see to it that our activities are of a certain kind, since any variations in them will be reflected in our characteristics. Hence it is no small matter whether one habit or another is inculcated in us from early childhood; on the contrary, it makes a considerable difference, or, rather, all the difference. (II, 1103b)
 technē (τέχνη): the skill, art, or craft and general know-how, the possession of which enables a person to produce a certain product. The term is used not only to describe, for example, the kind of knowledge which a shoemaker needs to produce shoes, but also to describe the art of a physician which produces health, or the skill of a harpist which produces music. Thus technē as an applied science concerned with production is often contrasted with epistēmē, which is pure scientific knowledge for its own sake.
 hexis (ἕξις): characteristic, also trained ability, characteristic condition, characteristic attitude. A noun related to the verb echein, ‘to have,’ ‘hold,’ ‘hold as a possession,’ ‘be in a certain condition,’ designating a firmly fixed possession of the mind, established by repeated and habitual action. Once attained, it is ever present, at least in a potential form. The Latin interpreters of Greek philosophy rendered the term by habitus, a word which well retains the original relation with habēre = echein. Hence ‘habit’ has often been used as an English equivalent.
Aristotle. Nicomachean Ethics. Trans. Martin Ostwald. Prentice Hall, 1999.