As illustrating how, as we know more about the details of medical history, the beginnings of medical science and medical practice are pushed back farther and farther, a discussion in the _Berliner klinische Wochenschrift_ a dozen years ago is of interest. Professor Ernest von Leyden, in sketching the history of the taking of the pulse as an important aid in diagnostics, said that John Floyer was usually referred to as the man who introduced the practice of determining the pulse rate by means of the watch. His work was done about the beginning of the eighteenth century. Professor von Leyden suggested, however, that William Harvey, the English physiologist, to whom is usually attributed the discovery of the circulation of the blood, had emphasized the value of the pulse in medical diagnosis, and also suggested the use of the watch in counting the pulse. Professor Carl Binz, of the University of Bonn, commenting on these remarks of Professor von Leyden, called attention to the fact that more than a century before the birth of either of these men, even the earlier, to whom the careful measurement of the pulse rate is thus attributed as a discovery, a distinguished German churchman, who died shortly after the middle of the fifteenth century, had suggested a method of accurate estimation of the pulse that deserves a place in medical history. This suggestion is so much in accord with modern demands for greater accuracy in diagnosis that it seems not inappropriate to talk of it as the first definite attempt at laboratory methods in the department of medicine. The maker of the suggestion, curiously enough, was not a practising physician, but a mathematician and scholar, Cardinal Nicholas of Cusa, who is known in history as Cusanus from the Latin name of the town Cues on the Moselle River, some twenty-five miles south of Treves, where he was born. His family name, Nicholas Krebs, has been entirely lost sight of in the name derived from his native town, which is the only reason why most of the world knows anything about that town. Cardinal Cusanus suggested that in various forms of disease and at various times of life, as in childhood, boyhood, manhood, and old age, the pulse was very different. It would be extremely valuable to have some method of accurately estimating, measuring, and recording these differences for medical purposes. At that time watches had not yet been invented, and it would have been very difficult to have estimated the time by the clocks, for almost the only clocks in existence were those in the towers of the cathedrals and of the public buildings. The first watches, Nuremberg eggs, as they were called, were not made by Peter Henlein until well on into the next century. The only method of measuring time with any accuracy in private houses was the clepsydra or water-clock, which measured the time intervals by the flow of a definite amount of water. Cardinal Cusanus suggested then that the