Aristotle, Nicomachean Ethics
H. Rackham, Ed.

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. [4] It remains therefore that it is a truth-attaining rational quality, concerned with action in relation to things that are good and bad for human beings. [5]

Hence men like Pericles are deemed prudent, because they possess a faculty of discerning what things are good for themselves and for mankind and that is our conception of an expert in Domestic Economy or Political Science.

（This also accounts for the word Temperance,³ which signifies ‘preserving prudence.’ [6] And Temperance does in fact preserve our belief as to our own good; for pleasure and pain do not destroy or pervert all beliefs, for instance, the belief that the three angles of a triangle are, or are not, together equal to two right angles, but only beliefs concerning action. The first principles of action are the end to which our acts are means; but a man corrupted by a love of pleasure or fear of pain, entirely fails to discern any first principle,⁴ and cannot see that he ought to choose and do everything as a means to this end, and for its sake; for vice tends to destroy the sense of principle.⁵）

It therefore follows that Prudence is a truth-attaining rational quality, concerned with action in relation to the things that are good for human beings. [7]

Moreover, we can speak of excellence in Art,⁶ but not of excellence in Prudence. Also in Art voluntary error is not so bad as involuntary, whereas in the sphere of Prudence it is worse, as it is in the sphere of the virtues. It is therefore clear that Prudence is an excellence or virtue, and not an Art. [8]

Of the two parts of the soul possessed of reason, Prudence must be the virtue of one, namely, the part that forms opinions⁷; for Opinion deals with that which can vary, and so does Prudence. But yet Prudence is not a rational quality merely, as shown by the fact that a purely rational faculty can be forgotten, whereas a failure in Prudence is not a mere lapse of memory.⁸ 6.

Scientific Knowledge is a mode of conception dealing with universals and things that are of necessity; and demonstrated truths and all scientific knowledge （since this involves reasoning） are derived from first principles. Consequently the first principles from which scientific truths are derived cannot themselves be reached by Science; nor yet are they apprehended by Art, nor by Prudence. To be matter of Scientific Knowledge a truth must be demonstrated by deduction from other truths;