Some of this very different story is told only too incompletely in this volume. It would take many volumes to give all the details of it. Readers will find here at least such references to the actual documentary history as will form a good basis for definite knowledge of the genuine relations of the Popes to science. The series of new appendices in this edition, especially those on Papal Physicians, Science in America, and the original Papal documents so often quoted, but seldom seen entire, is meant to supply material for the correction of many false notions that are unfortunately prevalent. They present historical matter that has not been readily available hitherto in English-speaking countries and that has nowhere been easy of access in the form here given. Appendix VII by Rev. Father Leahy on _The Fathers of The Church and Science_ presents a controverted point of history to persuasion. Appendix IX shows how amusing and amazing was Professor Draper's lack of knowledge of the history of science and above all of medicine and surgery when he wrote his "histories" that were so widely read and accepted because we in America knew no better for the moment. {v} PREFACE For years, as a student and physician, I listened to remarks from teachers and professional friends as to the opposition of the Popes to science, until finally, much against my will, I came to believe that there had been many Papal documents issued, which intentionally or otherwise hampered the progress of science. Interest in the history of medicine led me to investigate the subject for myself. To my surprise, I found that the supposed Papal opposition to science was practically all founded on an exaggeration of the significance of the Galileo incident. As a matter of history, the Popes were as liberal patrons of science as of art. In the Renaissance period, when their patronage of Raphael and Michel Angelo and other great artists did so much for art, similar relations to Columbus, Eustachius, and Caesalpinus, and later to Steno and Malpighi, our greatest medical discoverers, had like results for science. The Papal Medical School was for centuries the greatest medical school in Europe, and its professors were the most distinguished medical scientists of the time. This is a perfectly simple bit of history that anyone may find for himself in any reliable history of medicine. The medical schools were the scientific departments of the universities practically down to the nineteenth century. In them were studied botany, zoology and the biological sciences generally, chemistry, physics, mineralogy and even astronomy, because of the belief that the stars influenced human constitutions. The Popes in fostering medical schools (there were four of them in the Papal dominions, and two of them, Bologna and Rome, were the greatest medical schools for several centuries) were acting as wise and beneficent patrons of science. Many of the greatest scientists of the