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,Or ‘to one corrupted by pleasure or pain this end does not seem to be a first principle at all.’ 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.i.e., to destroy our perception of the true end of life, which constitutes the major premise of the practical syllogism.）

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.