and chemistry into semi-magical lines, an evil tendency from which the Arabic school never quite freed itself. A considerable time elapsed before the Arabic speaking community produced any original writers on medicine. About the end of the third century we find Abu l-Abbas Ahmad b. Thayib as-Sarakhsi, a pupil of al-Kindi, who is stated to have written a treatise on the soul, an abridgment of Porphyry’s _Isagoge_, and an introductory manual of medicine (Masudi. ii. 72). At that time medical studies were still very largely in Christian and Jewish hands, and we find the Syriac physician John ben Serapion (end of 9th cent. A.D.) writing in Syriac medical pandects which were circulated in two editions, the latter of which was translated into Arabic by several writers independently and long afterwards into Latin by Gerard of Cremona. The father of Arabic medicine proper was Abu Bakr Muhammad b. Zakariyya ar-Razi (d. A.H. 311-320 = A.D. 923-932) who was known to Latin mediæval writers as “Razes,” a student of music, philosophy, literature, and finally medicine. In his medical pandects he uses both Greek and Indian authorities, and the introduction of these latter in subordination to the classic authorities used at Alexandria was the really important contribution made by the Arabic students to the progress of science. Unfortunately ar-Razi’s work suffered from the defect that it greatly lacks order and arrangement, it is a collection of more or less separate treatises, and so not at all convenient to use. For this reason more perhaps than any other he was replaced by Ibn Sina (Avicenna) whose work, if anything, errs in the opposite direction and suffers from an extremely elaborate arrangement and systematization. It will be noticed that with the Arabic writers, as with their Syriac predecessors, the leading medical writers were usually also exponents of logic and commentators on Aristotle as well as Galen. The Khalif al-Mansur was the patron who did most to attract the Nestorian physicians to the city of Baghdad which he had founded, and he was also a prince who did much to encourage those who set themselves to prepare Arabic translations of Greek, Syriac, and Persian works. Still more important was the patronage given by the Khalif al-Ma´mun who in A.H. 217 (= A.D. 832) founded a school at Baghdad, suggested no doubt by the Nestorians and Zoroastrian schools already existing, and this he called the _Bayt al-Hikma_ or “House of Wisdom,” and this he placed under the guidance of Yahya b. Masawaih (d. A.H. 243 = A.D. 857), who was an author both in Syriac and Arabic, and learned also in the use of Greek. His medical treatise on “Fevers” was long in repute and was afterwards translated into Latin and into Hebrew.