It was of course the logical side of Galenism which chiefly commended it to the mediaeval Schoolmen, as to the essentially speculative Moslems. [Sidenote: The Renascence.] The year 1453, when Constantinople fell into the hands of the Turks, is often taken as marking the commencement of the Renascence. Among the many factors which tended to stimulate and awaken men's minds during these spacious times was the rediscovery of the Greek classics, which were brought to Europe by, among others, the scholars who fled from Byzantium. The Arabo-Scholastic versions of Aristotle and Galen were now confronted by their Greek originals. A passion for Greek learning was aroused. The freshness and truth of these old writings helped to awaken men to a renewed sense of their own dignity and worth, and to brace them in their own struggle for self-expression. Prominent in this "Humanist" movement was the English physician, Thomas Linacre (_c._ 1460-1524) who, having gained in Italy an extraordinary zeal for the New Learning, devoted the rest of his life, after returning to England, to the promotion of the _litterae humaniores_, and especially to making Galen accessible to readers of Latin. Thus the "_De Naturalibus Facultatibus_" appeared in London in 1523, and was preceded and followed by several other translations, all marked by minute accuracy and elegant Latinity. Two new parties now arose in the medical world--the so-called "Greeks" and the more conservative "Arabists." [Sidenote: Paracelsus.] But the swing of the pendulum did not cease with the creation of the liberal "Greek" party; the dazzling vision of freedom was to drive some to a yet more anarchical position. Paracelsus, who flourished in the first half of the 16th century, may be taken as typifying this extremist tendency. His one cry was, "Let us away with all authority whatsoever, and get back to Nature!" At his first lecture as professor at the medical school of Basle he symbolically burned the works of Galen and of his chief Arabian exponent, Avicenna. [Sidenote: The Renascence Anatomists.] But the final collapse of authority in medicine could not be brought about by mere negativism. It was the constructive work of the Renascence anatomists, particularly those of the Italian school, which finally brought Galenism to the ground. Vesalius (1514-64), the modern "Father of Anatomy," for dissecting human bodies, was fiercely assailed by the hosts of orthodoxy, including that stout Galenist, his old teacher Jacques Dubois (Jacobus Sylvius). Vesalius held on his way, however, proving, _inter alia_, that Galen had been wrong in saying that the interventricular septum of the heart was permeable (_cf._ present volume, p. 321). Michael Servetus (1509-53) suggested that the blood, in order to get from the right to the left side of the heart, might have to pass through the lungs. For his heterodox opinions he was burned at the stake.