Although Dionysius stated that the First Council of Nicaea in 325 sanctioned his method of dating Easter, that is only generally true. There was no formal canon – the Council was working with Canon 1 of the Council of Arles (314) which had decreed that the Christian Passover be celebrated "uno die et uno tempore per omnem orbem" (on one day and at one time through all the world) and had charged the bishop of Rome with fixing the date. A circular letter from the Emperor Constantine to bishops who did not attend records: