This enables him easily to survey as a whole his life and the course of the world, looking before and after; it makes him independent of the present, enables him to go to work deliberately, systematically, and with foresight, to do evil as well as to do good. But what he does he does with complete self-consciousness; he knows exactly how his will decides, what in each case he chooses, and what other choice was in the nature of the case possible; and from this self-conscious willing he comes to know himself and mirrors himself in his actions. In all these relations to the conduct of men reason is to be called _practical_; it is only theoretical so far as the objects with which it is concerned have no relation to the action of the thinker, but have purely a theoretical interest, which very few men are capable of feeling. What in this sense is called _practical reason_ is very nearly what is signified by the Latin word _prudentia_, which, according to Cicero (_De Nat. Deor._ ii., 22), is a contraction of _providentia_; while, on the other hand, _ratio_, if used of a faculty of the mind, signifies for the most part theoretical reason proper, though the ancients did not observe the distinction strictly. In nearly all men reason has an almost exclusively practical tendency; but if this also is abandoned thought loses the control of action, so that it is then said, “_Scio meliora, proboque, deteriora sequor_,” or “_Le matin je fais des projets, et le soir je fais des sottises_.” Thus the man does not allow his conduct to be guided by his thought, but by the impression of the moment, after the manner of the brute; and so he is called irrational (without thereby imputing to him moral turpitude), although he is not really wanting in reason, but in the power of applying it to his action; and one might to a certain extent say his reason is theoretical and not practical. He may at the same time be a really good man, like many a one who can never see any one in misfortune without helping him, even making sacrifices to do so, and yet leaves his debts unpaid. Such an irrational character is quite incapable of committing great crimes, because the systematic planning, the discrimination and self-control, which this always requires are quite impossible to him. Yet, on the other hand, he will hardly attain to a very high degree of virtue, for, however much inclined to good he may be by nature, those single vicious and wicked emotions to which every one is subject cannot be wanting; and where reason does not manifest itself practically, and oppose to them unalterable maxims and firm principles, they must become deeds.