Baillou, whose writings appeared posthumously under the Latin name, Ballonius, was born in Paris, the son of a famous mathematician and architect. After studying at the University of Paris where he concentrated especially in Latin, Greek, and philosophy, Baillou qualified in succession for the baccalaureate and the doctor's degrees.1 While preparing for the higher honors, he taught humanities and, upon completion of formal courses, was associated with the Faculty, serving eventually as Dean for a biennium beginning in 1580. He was a pupil of Jean Fernel and a follower of Hippocrates in his respect for the bedside observation of diseases. Exploiting his outstanding talents, he became a skillful physician, a brilliant teacher, and a student of epidemics. Baillou lived in Paris during the horrible period of the 16th century, with persecution and violence a way of death, and with squalor, filth, and pestilence spawning recurring epidemics as well as