Vincent of Lérins (400–445)

Formulated the rule: what has been believed everywhere, always, by all. Vincent of Lérins was a Gallic monk and author of early Christian writings. One example was the Commonitorium, c. 434, which offers guidance in the orthodox teaching of Christianity. Suspected of semi-Pelagianism, he opposed the Augustinian model of grace and was probably the recipient of Prosper of Aquitaine's Responsiones ad Capitula Objectionum Vincentianarum. His feast day is celebrated on 24 May.