To take a third case: all through later antiquity and the middle ages the science of medicine was based on the writings of two ancient doctors, Hippocrates and Galen. Galen was a Greek who lived at Rome in the early Empire, Hippocrates a Greek who lived at the island of Cos in the fifth century B. C. A great part of the history of modern medicine is a story of emancipation from the dead hand of these great ancients. But one little treatise attributed to Hippocrates was in active use in the training of medical students in my own day in Scotland and is still in use in some American Universities. It was the Oath taken by medical students in the classic age of Greece when they solemnly faced the duties of their profession. The disciple swore to honour and obey his teacher and care for his children if ever they were in need; always to help his patients to the best of his power; never to use or profess to use magic or charms or any supernatural means; never to supply poison or perform illegal operations; never to abuse the special position of intimacy which a doctor naturally obtains in a sick house, but always on entering to remember that he goes as a friend and helper to every individual in it. We have given up that oath now: I suppose we do not believe so much in the value of oaths. But the man who first drew up that oath did a great deed. He realized and defined the meaning of his high calling in words which doctors of unknown tongues and undiscovered countries accepted from him and felt to express their aims for well over two thousand years.