Aristotle, Nicomachean Ethics
H. Rackham, Ed.

[10] Now this faculty is not identical with Prudence, but Prudence implies it. But that eye of the soul of which we spoke¹ 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.