Thirty or forty years elapsed after Galen’s death before the Profession began to realize how great an authority he had become in all matters relating to medicine; not perhaps among the majority of physicians, but among the better educated and those more given to reasoning about the various problems in physiology and pathology. Then came the invasion of Rome by the Barbarians, and with it the scattering of nearly all those who were at the time practicing medicine in that great city. This was the beginning of the long period known as the Middle Ages, a period during which, so far as Italy and Gaul were concerned, the science of medicine made no advance whatever. The physicians living in a precarious manner in the towns, and the monks who practiced medicine in the country districts, took very little interest, as may readily be imagined, in the achievements of Galen. Through all those years they clung to the doctrines of the Methodists, as revealed to them in the work of Caelius Aurelianus, the favorite medical treatise of that period. It was only during the latter part of the Middle Ages that Galen’s teachings began once more to be appreciated at their true value; and, as time went on, they gained a stronger and stronger hold on the minds of medical men, until finally they held undisputed sway. Friedlaender, speaking of medicine in those dark times, uses these words: “Galen’s colossal personality loomed up throughout that long night as a brilliant guiding star to light the intricate pathways of medicine.” CHAPTER XVI THE INFLUENCE OF CHRISTIANITY UPON THE EVOLUTION OF MEDICINE The religion established by Jesus Christ in Judea during the early part of the first century remained confined within the limits of that region for a number of years, but already during the latter half of that period groups of Christians were to be found in every part of the Roman Empire, and in certain localities the membership of the new church had increased so greatly in numbers as to excite the alarm and hostility of the temple priests and of the governing officials. Persecutions, especially in the city of Rome and at the instigation of Nero, became more and more frequent and more and more pitiless, but they failed utterly to destroy the new religion, so firmly was it rooted in the followers of Jesus Christ. As a matter of fact its spread was checked for only a few years, and then its adherents increased in numbers more rapidly than ever. Neuburger, in his “History of Medicine,” makes the following quotation from the account which Dionysius of Alexandria gives of the great plague that occurred during the third century A. D.: