orderliness of life――all these became for him preliminary stages in the full participation in the ethical Good. They came to have for him a relative value, as expressed in the _Philebus_, _Republic_, and _Symposium_. =2. The Four Cardinal Virtues.= But Plato went farther, and was not content merely to point out the place of human conduct in the twofold world. He developed his theory of ethics systematically. He classified the virtues on the basis of his threefold division of the soul. Naturally enough, in his first draft of his theory, Plato followed Socrates in reducing the single virtues to one, viz., the virtue of knowledge. In his second drafting, however, in the later dialogues, he assumed their distinct independence, and he reflected upon their respective spheres. A virtue corresponds to each part of the soul. Each part has its own perfection, which is its virtue. Moreover, in so far as one or another part of the soul preponderates in different men, so far are they suited to developing the corresponding virtue. { Rational nature――in brain (Wisdom) Soul (Justice) { Irrational { Noble part――in heart (Courage) { nature { Ignoble part――in liver (Temperance) From the above scheme it will be observed that the rational nature has the brain as its organ and reaches its perfection or virtue in Wisdom; that the ignoble irrational nature has the liver as its organ, and reaches its virtue in self-control or Temperance. Finally, since the perfection of the whole soul consists in the orderly relation of its single parts, so subordinated and regulated that the soul can reach its highest perfection, the fourth and highest virtue is Justice. _The four cardinal virtues are Temperance, Courage, Wisdom, and Justice._