In 330 A. D. the new capital of the Roman Empire was established in Byzantium, afterward called Constantinople, and Rome, which for hundreds of years had been the metropolis of the world and the source from which a large part of Roman history had emanated, was given a subordinate position. Then followed, in 410 A. D., the conquest of the latter city by the Visigoths, a horde of uneducated Barbarians who had felt the might of Rome in previous years, and who now doubtless took immense satisfaction in humiliating her and in destroying her valuable possessions. There are good reasons for believing that, when the Emperor Constantine established his residence in Byzantium, the leading physicians of Rome followed him; and it is not likely that many of those who, for one reason or another, preferred to remain in the old capital, continued to do so after it became known that the Barbarians were approaching the city. But the migration of these physicians to the new capital did not mean a renewal there of the scientific activity which had characterized the growth of Greek medicine in Rome during the first two centuries of the Christian Era. It is probable that the fugitives, being obliged to travel with the smallest amount of baggage possible, left the major part of their books and papyrus rolls behind, hoping, no doubt, that they might be able at some later date to recover them. But the favorable occasion never arrived, and thus a great deal of valuable medical literature entirely disappeared. The loss, however, might have been even more serious than it was if the Christian church had not already (during the third century) begun to establish monasteries in secluded and inaccessible spots. It was to these institutions that not only books of a religious character, but also those relating to the science of medicine, were transported for safe keeping during the early Middle Ages. Farther on, I shall have occasion to refer to this subject again and to discuss more fully certain other benefits which accrued to medical science from these monastic institutions.