In the early Middle Ages the Jewish physicians played a role of the first importance as preservers and transmitters of ancient knowledge. With the fall of Rome the broad stream of Greek science in western Europe entered the sud of mediævalism. It filtered through in three streams--one in South Italy, the other in Byzantium, and a third through Islam. At the great school of Salernum in the tenth, eleventh and twelfth centuries, we find important Jewish teachers; Copho II wrote the Anatomia Porci, and Rebecca wrote on fevers and the fœtus. Jews were valued councillors at the court of the great Emperor Frederick. With the Byzantine stream the Jews seem to have had little to do, but the broad, clear stream which ran through Islam is dotted thickly with Hebrew names. In the eastern and western Caliphates and in North Africa were men who to-day are the glory of Israel, and bright stars in the medical firmament. Three of these stand out preëminent. The writings of Isaac Judæus, known in the Middle Ages as Monarcha Medicorum, were prized for more than four centuries. He had a Hippocratic belief in the powers of nature and in the superiority of prevention to cure. He was an optimist and held strongly to the Talmudic precept that the physician who takes nothing is worth nothing. Rabbi ben Ezra was a universal genius and wanderer, whose travels brought him as far as England. His philosophy of life Browning has depicted in the well-known poem, whose beauty of diction and clarity of thought atone for countless muddy folios. _Maimonides: Prince Among Physicians_