He thinks that the relation between the body and the soul is determined by the soul. And seeing that in this way the circumstances and sufferings of the soul admit of being discerned by means of the physiognomy, the medical man has to be at the same time a physician of the soul. Therefore he drew up a system of spiritual medicine,—a kind of Dietetic of the Soul. The precepts of Muslim law, like the prohibition of wine, and so on, gave him no concern, but his freethinking seems to have led him into pessimism. In fact he found more evil than good in the world, and described inclination as the absence of disinclination. High though the value was which Razi put upon Aristotle and Galen, he did not give himself any special trouble to gain a more profound comprehension of their works. He was a devoted student of Alchemy, which in his view was a true art, based on the existence of a primeval matter,—an art indispensable to philosophers, and which, he believed, had been practised by Pythagoras, Democritus, Plato, Aristotle and Galen. In opposition to Peripatetic teaching he assumed that the body contained in itself the principle of movement, a thought which might certainly have proved a fruitful one in Natural Science, if it had been recognized and farther developed. Razi’s Metaphysic starts from old doctrines, which his contemporaries ascribed to Anaxagoras, Empedocles, Mani and others. At the apex of his system stand five co-eternal principles,—the Creator, the Universal Soul, the First or Primeval matter, Absolute Space, and Absolute Time or Eternal Duration. In these the necessary conditions of the actually existing world are given. The individual sense-perceptions, generally, presuppose an existing Matter, just as the grouping of different perceived objects postulates Space. Perceptions of change farther constrain us to assume the condition of Time. The existence of living beings leads us to recognize a Soul; and the fact that some of these living beings are endowed with Reason, i.e.—have the faculty of bringing the Arts to the highest perfection,—necessitates our belief in a wise Creator, whose Reason has ordered everything for the best.