to Harvey in his discovery of the circulation. Guy of Chauliac, whose innovations in surgery reestablished that science on a firm basis, was not only one of the most cultured, but also the most practical surgeon of his time. He had great reverence for the works of Galen, Albucasis, and others of his noted predecessors; but this reverence did not blind him to their mistakes nor prevent him from using rational methods of treatment far in advance of theirs. His practicality is shown in some of his simple but useful inventions for the sick-room, such as the device of a rope, suspended from the ceiling over the bed, by which a patient may move himself about more easily; and in some of his improvements in surgical dressings, such as stiffening bandages by dipping them in the white of an egg so that they are held firmly. He treated broken limbs in the suspended cradle still in use, and introduced the method of making "traction" on a broken limb by means of a weight and pulley, to prevent deformity through shortening of the member. He was one of the first physicians to recognize the utility of spectacles, and recommended them in cases not amenable to treatment with lotions and eye-waters. In some of his surgical operations, such as trephining for fracture of the skull, his technique has been little improved upon even in modern times. In one of these operations he successfully removed a portion of a man's brain. Surgery was undoubtedly stimulated greatly at this period by the constant wars. Lay physicians, as a class, had been looked down upon during the Dark Ages; but with the beginning of the return to rationalism, the services of surgeons on the battle-field, to remove missiles from wounds, and to care for wounds and apply dressings, came to be more fully appreciated. In return for his labors the surgeon was thus afforded better opportunities for observing wounds and diseases, which led naturally to a gradual improvement in surgical methods. FIFTEENTH-CENTURY MEDICINE The thirteenth and fourteenth centuries had seen some slight advancement in the science of medicine; at least, certain surgeons and physicians, if not the generality, had made advances; but it was not until the fifteenth century that the general revival of medical learning became assured. In this movement, naturally, the printing-press played an all-important part. Medical books, hitherto practically inaccessible to the great mass of physicians, now became common, and this output of reprints of Greek and Arabic treatises revealed the fact that many of the supposed true copies were spurious. These discoveries very naturally aroused all manner of doubt and criticism, which in turn helped in the development of independent thought.