Full Idea
One cannot be prudent (have practical reason) without being good.
Gist of Idea
One cannot be prudent without being good
Source
Aristotle (Nicomachean Ethics [c.334 BCE], 1144a33)
Book Reference
Aristotle: 'Ethics (Nicomachean)', ed/tr. ThomsonJ A K/TredennickH [Penguin 1976], p.223
A Reaction
I suspect that for Aristotle this is more of a tautology than an observation. We might think of a very clever criminal as having 'phronesis' (practical reason), but Aristotle simply wouldn't, though he has no simple explanation for his view.