Complex sentence: He entered Lérins Abbey on Île Saint-Honorat, where under the pseudonym Peregrinus he wrote "Commonitorium",, about three years after the Council of Ephesus.
Split into simpler sentences: He entered Lérins Abbey on Île Saint-Honorat, where under the pseudonym Peregrinus he wrote "Commonitorium",. About three years after the Council of Ephesus.