Louis Pasteur, the father of modern medicine, brought scorn upon himself from the older members of the French Academy of Medicine when he explained to them the discoveries he had made through his microscope. Nevertheless he continued his experiments for fifteen years and proved his theories so successfully by actual cures that at another meeting of the Academy he was heaped with honors. The modern physician is a descendant of Pasteur. The old untidy family advisor is more a remnant of the days when the efficacy of herbs was thought to lie in the incantations breathed over them by the "medicine man" and when exposure to the moon often brought a deathly sickness. It was the spirit of the French scientist which drove malaria out of Cuba, and which acting through the men trained in the medical schools may yet discover the cause of sleeping sickness and combat the plague in the East which is now wining out whole towns of India. Dr. Thayer, himself a member of the French Academy and actively engaged in the advancement of medicine at Johns Hopkins Hospital can explain the challenge which disease still throws out to the educated man.