4. The science of Medicine, which on obvious grounds was favoured by the ruling powers, appears to have proved somewhat more useful. Its interests furnished one of the reasons, and not the least considerable, which induced the Caliphs to commission so many men to translate Greek authors. It is therefore not to be wondered at that the teachings of Mathematics and Natural Science, together with Logic, also affected Medicine intimately. The old-fashioned doctor was disposed to be satisfied with time-honoured magical formulae, and other empirical expedients; but modern society in the ninth century required philosophical knowledge in the physician. He had to know the “natures” of foods, stimulants or luxuries, and medicaments, the humours of the body, and in every case the influence of the stars. The physician was brother to the astrologer, whose knowledge commanded his respect, because it had a more exalted object than medical practice. He had to attend the lectures of the alchemist, and to practise his art in accordance with the methods of Mathematics and Logic. It was not enough for the fanatics of education in the ninth century that a man had to speak, believe and behave in accordance with Qiyas,—that is to say, with logical correctness: he must, over and above, submit to be treated medically in accordance with Qiyas. The principles of Medicine were discussed in learned assemblies at the court of Wathik (842–847) like the foundations of Doctrine and Morals. The question, in fact, was asked, prompted by a work of Galen’s, whether Medicine relies upon tradition, experience or rational knowledge, or whether on the other hand it derives its support from the principles of Mathematics and Natural Science by means of logical deduction (Qiyas). 5. The Natural Philosophy, which has just been rapidly sketched, actually stood for Philosophy with the most of the scholars of the ninth century, as contrasted with theological dialectic, and was styled Pythagorean. It lasted even into the tenth century, when its most important representative was the famous physician Razi († 923 or 932). Born in Rai he received a mathematical education and studied Medicine and Natural Philosophy with great diligence. He was averse to dialectic and was only acquainted with Logic as far as the categorical figures of the First Analytics. After having practised as director of the hospital in his native city and in Bagdad, he entered upon his travels and resided at various princely courts, amongst others at the court of the Samanid Mansur ibn Ishaq, to whom he dedicated a work on Medicine. Razi has a high opinion of the medical profession and of the study which it demands. The wisdom of a thousand years, contained in books, he prizes more than the experiences of the individual man gained in one short life, but he prefers even these to deductions of the “Logicians” which have not been tested by experience.