Aristotle, Nicomachean Ethics
H. Rackham, Ed.

of the acts themselves. [8] Now rightness in our choice of an end is secured by Virtue¹; but to do the actions that must in the nature of things be done in order to attain the end we have chosen, is not a matter for Virtue but for a different faculty.

We must dwell on this point to make it more clear. [9] There is a certain faculty called Cleverness, which is the capacity for doing the things aforesaid that conduce to the aim we propose, and so attaining that aim. If the aim is noble, this is a praiseworthy faculty: if base, it is mere knavery; this is how we come to speak of both prudent men and knaves as clever. [10] Now this faculty is not identical with Prudence, but Prudence implies it. But that eye of the soul of which we spoke² cannot acquire the quality of Prudence without possessing Virtue. This we have said before, and it is manifestly true. For deductive inferences about matters of conduct always have a major premise of the form ‘Since the End or Supreme Good is so and so’ （whatever it may be, since we may take it as anything we like for the sake of the argument）; but the Supreme Good only appears good to the good man: vice perverts the mind and causes it to hold false views about the first principles of conduct. Hence it is clear that we cannot be prudent without being good.