Peter, one of the ablest physicians of the 16th century, was born at Fontenai le Comte in Poitou. He studied at Paris; and, having taken his doctor's degree, bent his thoughts to the reforming of physic, by restoring the precepts of Hippocrates and Galen, and exploding the maxims of the Arabians: for this purpose he publicly explained Galen's works, instead of those of Avicenna, Rhasis, and Messue. He afterwards resolved to travel to acquire the knowledge of plants; and going to Portugal, practised physic in the city of Eibora. His new method of bleeding in pleurisies, on the side where the pleurisy was, raised a kind of civil war among the Portuguese physicians; it was brought before the university of Salamanca, who at last gave judgment, that the opinion ascribed to Brissot was the pure doctrine of Galen. The partizans of Denys, his opponent, appealed in 1529 to the emperor, to prevent the practice, as being attended with destructive consequences; but Charles III. duke of Savoy happening to die at this time of a pleurisy, after having been bled on the opposite side, the prosecution dropped. He wrote an Apology for his practice; but died before it was published, in 1552; but Anthony Luceus, his friend, printed it at Paris three years after. Renatus Moreau procured a new edition of it at Paris, in 1622; and annexed to it a treatise entitled De missione sanguinis in pleuritide, together with the Life of Brissot.

John Peter, leader of the Brissotine party in the French revolution. See Supplement.