The French clergyman John Gerson (1363-1429) was a leader of the Conciliar movement. He is known for his efforts in ending the Great Schism.

John Gerson was born Jean Charlier at Gerson on Dec. 13, 1363. He attended the College of Navarre at the University of Paris, where he was taught by Pierre d'Ailly, who became his close friend. He became chancellor of the University of Paris in 1395, when d'Ailly resigned the post. Gerson's early actions at the university were not particularly notable, but they reflect the general opinion of the times. Thus in 1387 he demanded the condemnation of the Dominican monk Jean de Montson, who denied the Immaculate Conception; and he warned students away from "immoral" popular literature.

Gerson emerged as a firebrand reformer only when the university took a leading role in ending the Great Schism. Since 1378 the Church had been divided between rival popes, one at Rome...