The motion of passive substance towards the active form, _i.e._, the realisation of the Possible, leads up to the idea of development, of genesis (though not, indeed, in the modern sense) on which Plato’s speculations had made shipwreck, and passes over Plato’s rigid Eleatism to join hands with Heraclitus, the philosopher of change, with whom Aristotle sees the ultimate cause of all motion and all things in the Deity, itself as eternal as the world, which “yearns towards It as the bridegroom towards the bride.” Thus soul, too, is the pattern of the body, hence the purpose of its being. The body is but the instrument (_organon_) of the soul. Thus Aristotle first coins the name and idea of organic being and draws a sharp distinction between these animate creatures (plants, animals, and man) and inanimate nature. In ethics and politics his speculation treads in the footsteps of Plato, save that, in this province of thought also, he mitigates the uncompromising rigourism of the master by his innate bias towards the historically-established and practically-possible, and turns it to more profitable uses. The ethico-political speculations of both are, however, adapted to the aristocratic class at that time dominant in Greece. Alexander, the pupil of Aristotle, conquered the East during his master’s life-time, but the philosopher’s opinion that the newly acquired continent should be governed by other laws than those of Hellas was not practically feasible. His ethics failed him utterly in face of the new political situation thus created. III At this juncture the cosmopolitan Cynicism, which had outgrown the narrow particularism of Hellenism as early as the time of Antisthenes, and the Stoicism which was built upon its foundation later on, proved the form best fitted to the times. Zeno, sprung of Phœnician blood and brought up in Cyprus, that is on semi-Asiatic soil, elaborated this theory of life at Athens, whither he came shortly after the death of Aristotle (about 320). After the dualism that had prevailed from Anaxagoras to Plato and Aristotle, in which God and the World were set over against one another as antagonistic principles, Zeno’s theory harks back to the monistic tendency of the Ionic period. Like that, it is realistic, nay, grossly materialistic, in contrast to the Idealism of Athenian philosophy. The result is a consistent Pantheism in which soul and body represent the analogon to God and the World. Both are of the same essential nature, and only temporarily divided by transitory differentiation of manifestation. Zeno’s morality is rigorous, and aims not at the moderation of the passions (like that of Plato and Aristotle) but at their extirpation. The inexorable law that holds the world and man in bonds from which there is no escape, exacts obedience, and to render it voluntarily is virtue.