It is not unlikely that the difficult personal circumstances in which the Jews were placed had a good deal to do at all times with stimulating their ambitions and making them accomplish all that was in them. Certain it is that at all times we find a wonderful power in the people to rise above their conditions. With them, however, as with other peoples, luxury, riches, comfort, bring a surfeit to initiative and the race does not accomplish so much. At various times in the early Middle Ages, particularly, we find Jewish physicians doing great work and obtaining precious acknowledgment for it in spite of the most discouraging conditions. Later it is not unusual to find that there has been a degeneration into mere money-making as the result of opportunity and consequent ease and luxury. At a number of times, however, both in Christian and in Mohammedan countries, great Jewish physicians arose whose names have come to us and with whom every student of medicine who wants to know something about the details of the course of medical history must be familiar. There are men among them who must be considered among the great lights of medicine, significant makers always of the art and also in nearly all cases of the science of medicine. A little consideration of the history of the Jewish people and their great documents eliminates any surprise there may be with regard to their interest in medicine and successful pursuit of it during the Middle Ages. The two great collections of Hebrew documents, the Old Testament and the Talmud, contain an immense amount of material with reference to medical problems of many kinds. Both of these works are especially interesting because of what they have to say of preventive medicine and with regard to the recognition of disease. Our prophylaxis and diagnosis are important scientific departments of medicine dependent on observation rather than on theory. While therapeutics has wandered into all sorts of absurdities, the advances made in prophylaxis and in diagnosis have always remained valuable, and though at times they have been forgotten, re-discovery only emphasizes the value of preceding work. It is because of what they contain with regard to these two important medical subjects that the Old Testament and the Talmud are landmarks in the history of medicine as well as of religion.