Besides philosophy and theology we find a considerable interest in medicine and the two sciences of chemistry and astronomy which were treated as allied to it, for astronomy, regarded from the astrological point of view, was supposed to be closely associated with the conditions of life and death, of health and disease. Medical studies were especially attached to the school of Alexandria. Philosophy proper had been so largely taken over by theology that the secular investigators were rather impelled to turn to the natural sciences and as a centre of medical and allied studies the ancient school of Alexandria continued its development without loss of continuity, but under changed conditions. John Philoponus, or John the Grammarian, as he was called, was one of the later commentators on Aristotle and also one of the early lights of this medical school. The date of his death is not known, but he was teaching at Alexandria at the time when Justinian closed the schools at Athens in A.D. 529. The next great leader of this school was Paul of Aegina who flourished at the time of the Muslim conquest, and whose works long served as popular manuals of medicine. The founders of the medical school at Alexandria established a regular course of education for the training of medical practitioners, and for this purpose selected sixteen works of Galen, some of which were re-edited in an abridged form, and were made the subject of regular explanatory lectures. At the same time the school became a centre of original research, not only in medicine, but also in chemistry and other branches of natural science. Thus, on the eve of the Muslim conquest Alexandria had become a great home of scientific enquiry. To some extent this was unfortunate as the existing traditions in Egypt directed those investigations very much into obscurantist lines and tended to the use of magical forms, talismans, etc., and to introduce an astrological bias. This afterwards became the great defect of Arabic medicine as appears later even in mediæval Padua, but it was not the fault of Islam, it was an inheritance from Alexandria. Such material as remains of Syriac research shows us a saner and sounder method in vogue there, but Alexandria had eclipsed the Syrian scientists at the time of the Muslim invasion, at least in popular esteem, and this was a determining factor in directing Arabic research into these astrological by-paths.