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.
Letter 13 is offered here in the translation by A. Fitzgerald. It was written in 412 and was, in spite of the address, directed to more than one person. Letters announcing the paschal date were, back then, quite common.
Letter 13: Circular Letter announcing the Paschal Date
 To Peter the Elder
May God direct my every deed and word. I have just sent you the carrier with the Paschal letters, announcing the date of the holy festival as the nineteenth of Pharmuthi,note[14 April.] so that the night which precedes the day in question may also be consecrated to the mystery of the Resurrection.
 Show the messenger every consideration both on his arrival and at his departure. Let him have a change of horses each time. This is only fair to him, for he runs the risk of falling into the hands of armed enemies in undertaking to traverse so hostile a country in order to save an old ancestral custom of the Church from disappearing.
 This letter also begs the city to offer up prayers for me. The city ought thus to understand the imprudence it committed towards me in appointing one to the priesthood who had not sufficient confidence in his mission to enable him to go to God and pray on behalf of the whole people, but one who has need of the prayers of the people for his own salvation.
 A conjunction of circumstances has brought this gathering here at the very moment when I was trying to write to you. A Synod is now in session here, attended by many prelates. If I can say none of the things which you are accustomed to hear, there must be forgiveness for me and blame to yourselves, for instead of choosing one deep in the knowledge of the scriptures, you have selected one who is ignorant of them.