There are two classes of virtues based on the two kinds of rational life,――the practical virtues and the dianoetic virtues. The practical virtues are those of conduct based upon the rational control of the impulses; the dianoetic virtues are those of intellectual activity based upon the development of the perceptions. The perfect moral development of human nature will consist (1) in the perfect development and true regulation of the feelings and desires in moral excellence; and (2) a perfect development of the intellectual faculties for rational culture. (a) The Practical Virtues. The essential thing for the individual to regard, therefore, is the training of his will by right rational insight. He should seek to direct his impulses by reason, and not only once but so many times that the impulses will become rational habits. This is what Aristotle means by training in virtue. It is continuity in rational activity; it is a permanent development toward reason; it is the unfolding of the real Self. Aristotle had regard for the facts of life when he differed from Socrates, who said that virtue is knowledge. Aristotle did not conceive the will as psychological power independent of the reason. He doubted if rational insight was more powerful than the impulses, when the test comes. Experience often shows that although we may know what is right, an impulse will often drive us into habits not guided by reason. This presupposes for Aristotle a will that is free to choose among the desires that one which will lead him along the path that reason points out. It is impossible to formulate a rule for the acquirement of the particular virtues. Each virtue must be treated by itself. The only principle for guidance is that the reason should always seek the mean between two extremes. Thus courage is the mean between cowardice and rashness; temperance between intemperance and insensibility; friendliness between obsequiousness and brusqueness, etc. Moderation is the watchword in the cultivation of the practical virtues. (b) The Dianoetic Virtues are the means toward the attainment of pure rationality for one’s self. The dianoetic virtues are higher than the practical. They unfold the pure formal activity of the Nous, and give the most noble and perfect pleasure. Man finds through them his possible participation in the divine happiness. These intellectual virtues may be either theoretical or practical insight; in the latter case, Aristotle means knowledge of the right in art, and knowledge of justice. But the purest is Wisdom (θεωρία), which is knowledge for its own sake. It is the knowledge that God has of himself. Man may approximate this.