At the age of twenty-one, those young men who have successfully completed the State system of training become citizens or politicians, and begin to exercise the functions of such. These are of two kinds, (1) active, practical, or executive, and (2) deliberative, theoretical, or legislative. As action must, on the one hand, be vigorous, and, on the other, guided by deliberation, which requires large experience, the functions of the State must be so arranged that the active duties fall to the young and robust, the deliberative to the elderly and mature. The distinguishing virtue of the former is fortitude, with endurance or patience; that of the latter philosophy. Both equally have self-control and justice. In this way does Aristotle distribute Plato's four cardinal virtues. When young men first become citizens, they are assigned to posts of active service, civil and military, and thus study practical philosophy--Ethics and Politics--in a practical way. As they grow older, they gradually rise to posts demanding less practice and more thought, until at last they are admitted to the deliberative body, or council, when their active duties cease, and they are able to devote themselves to Speculative Philosophy or Theoretics. These men have now reached the end of life, as far as this world is concerned. They spend their days in cultured leisure, and the contemplation of divine things (θεωρία). The very oldest of them, those who are most conversant with divine things, are chosen as priests, so that they may, as it were, live with the gods, and these be worthily served. Thus gradually, almost insensibly, they pass from the world of time to that of eternity; from the imperfect activity of practice, whose end is beyond itself, to the perfect energy of contemplation, which is self-sufficient and the life of God. In this way Aristotle settles the vexed question with regard to the compatibility and relative value of the practical and the contemplative life. They are necessary complements of each other. Practice is the realization of what contemplation discovers in the pure energy of God, revealing itself in the world. Thus the practical life of man glides gradually into the contemplative life of God.