Lived in the 5th century, probably in northern Gaul. He held important public offices but, having freed himself from worldly cares, withdrew to the Lérins Monastery, founded by Saint Honoratus. In the monastery, he devoted himself to diligent study of the Holy Scriptures and the writings of the holy fathers, becoming known for his scholarship and eloquence.
Around the year 434, feeling the approach of death, he composed the 'Commonitorium', where he outlined the rules for distinguishing true faith from heresies, summarizing them in the formula: 'To consider as true faith that which is believed everywhere, always, and by all.' He defined Church Tradition as a living body that grows and develops while remaining itself. This work was very successful in the West and remains a reliable guide to Orthodox faith.
He peacefully completed his days in the monastery and fell asleep in Christ shortly before the year 450.
