Synesius of Cyrene (c.370-c.413) was a Neo-Platonic philosopher who became bishop of Ptolemais in the Cyrenaica. He left behind a small corpus of texts that offer much information about daily life in Late Antiquity, and about the christianization of the Roman world.
Synesius directed this letter (and letters 98, 99, 97, 133, 148, 149, and 96) to a wealthy Christian from Syria, who was a close friend and (probably) a fellow-student. Letter 45 was perhaps written in 412 and is offered in the translation of A. Fitzgerald.
Letter 45: A Call for Assistance
 To Olympius
Evil men from without are troubling our Church. Take steps against them. Only nails drive out nails.