Since virtue is the nucleus of happiness, by Aristotle's definition, it is not surprising that he loses no time in addressing the question of virtue: what it is and how it is attained. Yet this seems logically premature. The topic, he himself has indicated, is adverbial in nature, since the question was 'What is it for a human being to function well?''Well' he interpreted as 'in accordance with virtue or excellence'--another adverbial phrase, but one that invites detachment of the noun which then becomes a distinct object of inquiry. But now what of the verb which stands as subject to the adverb (and to contrary adverbs like 'badly' and 'indifferently')? What is it to function as a human being? Or what is that function such that to engage in it well or badly is to manifest one's human excellence or inferiority? We need an account of the activity or behaviour through which an individual's moral nature takes effect in the world, one of those effects being to reveal itself to others, if not also to its agent.
It is already clear what the broad answer will be: the functioning in question comprises emotional responses and actions. It might be unnecessary, in an inquiry on ethics, to press for more detail if it were always easy to recognise the instances. But often enough what from the outside appears as the person's own behaviour, expressing him as person or moral agent, is not really so. Not that it is necessarily anyone else's, but it is not his. To use the traditional term, it is not 'voluntary' (hekousion). As Aristotle says in the Eudemian Ethics, the term 'voluntary' is applied only to those things of which the person himself is cause and origin (1223 a 15-18). And Aristotle also declares that only those things of which we ourselves are the causes are proper objects of praise and censure (ibid. 11-14). Hence the class of the voluntary includes whatever is a proper object of praise or censure.
What are the objects of praise and censure? In the first place, behaviour, or what Aristotle loosely calls 'actions', though not all behaviour and not all (in that wide sense) actions. But Aristotle also holds that the moral characteristics developed, then manifested by, good and bad behaviour are themselves proper objects of praise and censure. This seems an uncontroversial position, but given Aristotle's conceptual