According to Aristotle (Ethic. Nic. lib. ii. ch. 1, 2, 3, and 4.), indeed, virtue did not so much consist in those moderate and right affections, as in the habit of this moderation. In order to understand this, it is to be observed, that virtue may be considered either as the quality of an action, or the quality of a person. Considered as the quality of an action, it consists, even according to Aristotle, in the reasonable moderation of the affection from which the action proceeds, whether this disposition be habitual to the person or not. Considered as the quality of a person, it consists in the habit of this reasonable moderation, in its having become the customary and usual disposition of the mind. Thus the action which proceeds from an occasional fit of generosity is undoubtedly a generous action, but the man who performs it, is not necessarily a generous person, because it may be the single action of the kind which he ever performed. The motive and disposition of heart, from which this action was performed, may have been quite just and proper: but as this happy mood seems to have been the effect rather of accidental humour than of any thing steady or permanent in the character, it can reflect no great honour on the performer. When we denominate a character generous or charitable, or virtuous in any respect, we mean to signify that the disposition expressed by each of those appellations is the usual and customary disposition of the person. But single actions of any kind, how proper and suitable soever, are of little consequence to show that this is the case. If a single action was sufficient to stamp the character of any virtue upon the person who performed it, the most worthless of mankind might lay claim to all the virtues; since there is no man who has not, upon some occasions, acted with prudence, justice, temperance, and fortitude. But though single actions, how laudable soever, reflect very little praise upon the {242} person who performs them, a single vicious action performed by one whose conduct is usually pretty regular, greatly diminishes and sometimes destroys altogether our opinion of his virtue. A single action of this kind sufficiently shows that his habits are not perfect, and that he is less to be depended upon, than, from the usual train of his behaviour, we might have been apt to imagine.