Aristotle, Nicomachean Ethics
H. Rackham, Ed.

But no one deliberates about things that cannot vary, nor about things not within his power to do. Hence inasmuch as scientific knowledge involves demonstration, whereas things whose fundamental principles are variable are not capable of demonstration, because everything about them is variable, and inasmuch as one cannot deliberate about things that are of necessity, it follows that Prudence is not the same as Science. Nor can it be the same as Art. It is not Science, because matters of conduct admit of variation; and not Art, because doing and making are generically different,¹ since making aims at an end distinct from the act of making, whereas in doing the end cannot be other than the act itself: doing well² is in itself the end.