Historians of science consider him worthy to be called the greatest living scientist of his time--the end of the sixteenth century. He was not only a scientific physician, but he was an authority in all the sciences related to medicine, and indeed had profound interests in every branch of physical science. His contemporaries looked up to him as a leader in scientific thought. To anyone who examines the question of the discovery of the circulation of the blood with freedom from bias, there can be no doubt but that the honor for this discovery has been unduly taken away from Caesalpinus in English-speaking countries, to be conferred solely on Harvey. Not that there is any wish to lessen the value of Harvey's magnificent original work, nor make little of his wonderful powers of observation, nor of the marvelous experimental and logical method by which he followed out his thoughts to their legitimate conclusion, but that I would insist on giving honor where honor is due, though most writers in English refuse to give Caesalpinus's claims a proper share of attention. The Italians have always declared that Caesalpinus was the real discoverer of the circulation, and there is no doubt that his career occurs just at that point in the evolution of the medical sciences, and especially anatomy and physiology in Italy, where this discovery would naturally come. Lest it should be thought, however, that my interest in the Popes and the Papal Medical School has led me to exaggerate the claims of {237} Caesalpinus as a great naturalist and medical scientist, I prefer to quote the description of him given by Professor Michael Foster in his lectures on the History of Physiology, delivered in this country as the Lane Lectures, at the Cooper Medical College in San Francisco, and published by the Cambridge University Press, 1901. Professor Foster was not one to exaggerate the claims of any Italian, and least of all of any Italian who might be supposed to have a claim that would stand against Harvey's. The soupçon of Chauvinism in his treatment of Servetus and Columbus in this regard is indeed rather amusing. He said:-- "Of a very different stamp to Columbus was Andreas Caesalpinus. Born at Arezzo in 1519, he was for many years Professor of Medicine at Pisa, namely, from 1567 to 1592, when he passed to Rome, where he became Professor at the Sapienza University and Physician to Pope Clement VIII., and where at a ripe old age he died in 1603. "If Columbus lacked general culture, Caesalpinus was drowned in it. Learned in all the learning of the ancients and an enthusiastic Aristotelian, he also early laid hold of all the new learning of the time. Naturalist as well as physician, he taught at Pisa botany as well as medicine, being from 1555 to 1575 Professor of Botany, with charge of the Botanic garden founded there in 1543, the first of its kind--one remaining until the present day."