The achievements in art and scholarship in this century are well known and universally recognized. It is seldom appreciated, however, that the century is almost as great in its {xxxvii} wonderful progress in science as it is in any other intellectual department. The foundations of our modern sciences were laid broad and deep at this time, and achievements of scientific generalization as well as accurate and detailed observation were made, that may be placed with confidence in comparison with those of any other time in the world's history, even our own. Copernicus' theory probably revolutionized men's thinking more with regard to the earth and the universe of which it forms a part than the thought of any man has ever done during the whole history of mankind. The great medical scientists of this period almost as effectually revolutionized men's thinking with regard to the constitution of men and animals as Copernicus had done with regard to the universe. Vesalius, called the father of modern anatomy, has left us a monument of genius in his work on the structure of the human body, and his famous contemporaries, Eustachius, another Columbus, the anatomist, and Caesalpinus as well as Servetus added to the knowledge of anatomy and physiology which Vesalius had so well begun. Servetus and Columbus described the circulation of the blood in the lungs about the same time; and shortly after the close of our period Caesalpinus, trained in the schools of this time, described the circulation of the blood in the body. In every department of biological science, in anatomy and physiology, in pathology, in botany, in zoology, in palaeontology, in ethnology and linguistics, in anthropology, noteworthy advances were made. Magnificent applications of the knowledge acquired were made for the benefit of man and animals, new plants for medicine were sought in distant countries and a great new development of medicine took place. None of the anatomists and physiologists of the time failed to use their knowledge for the increase of information with regard to disease and its treatment. Vesalius besides being a great anatomist was almost as great a pathologist and one of the epoch-making diagnosticians of medical history. He was the first since the Greeks to describe an aneurism, that is the pathological dilatation of an artery through disease or accident, and the first in the history of medicine to demonstrate the presence of such a condition on the living subject. Paracelsus, {xxxviii} Ambroise Paré, Linacre, John Caius and a whole host of great teachers in Italy are names to conjure with in the history of medicine and of surgery. There is probably no period in the world's history that has so many names famous in medicine that the world will never willingly let die.