Memnon was metropolitan bishop of Ephesus during the third ecumenical council.The Historicity of the Seven Sleepers of Ephesus .
At the Council of Ephesus At the Council he was a supporter of Cyril of Alexandria. Delays in the opening of the council were blamed by Nestorius on Memnon.Uthemann, Karl-Heinz, “Memnon of Ephesus”, in: Religion Past and Present. Consulted online on 29 December 2017
Memnon hosted the second session of the Council in his episcopal palace and at the fourth session Cyril and Memnon presented a formal protest against John of Antioch for convening a separate conciliabulum, which condemned both of them.Joseph F. Kelly,The Ecumenical Councils of the Catholic Church: A History (Liturgical Press, 2009).
Bassianus Reportedly out of jealousy, Memnon sought to get rid of Bassianus, a priest under him, by ordaining him to the bishopric of Evaza. Bassianus refused the position and in 444 became, by an irregular process, Memnon's second successor.[https://www.newadvent.org/cathen/02345a.htm John Bertram Peterson, "Bassianus" in The Catholic Encyclopedia (New York: Robert Appleton, 1907).
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