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 138, written in 395 and addressed to Herculian, a former fellow-student in Alexandria who had been forced to leave because of a mistake made by Synesius (see Letter 137), is a reproach to this friend's (lost) response to an earlier letter. The friendship survived: Herculian received not only Letter 137 and this letter, but also letters 139, 145, 140, 141, 142, 146, 143, and 144.
Letter 138 is offered here in the translation by A. Fitzgerald.
 To Herculian
I once heard one of our brilliant speakers praising the practice of letter-writing; and this very theme the sophist developed with a wonderful flow of eloquence. He hymned an encomium on it for various reasons, but particularly because of the letter's power to be a solace for unhappy loves, affording as it does in bodily absence the illusion of actual presence, for this missive seems itself to converse, thus fulfilling the soul's desire.
 In this way he celebrated the inventor of letters,note[Palamedes, a common theme for sophists, cf. Philostratus, Life of Apollonius 4.13.] and came to the conclusion that they were not a gift from any man but one from God to men. For my part I enjoy this sacred gift of God, and to whomsoever I needs must talk, if I cannot speak to him, at all events I can write, and this I often long to do. I then rejoice in those I love, and am present with them to the best of my power.
 Now as to you, if it may be said without bitterness, you seem to me to have changed your character along with your abode.note[In Letter 139, it seems to be Synesius who had left Alexandria.] If you do not abandon this way of separating yourself from those who have loved you without guile or affection, you are like the swallow who comes to live, so to speak, in the friendship of men with cries of joy, and who later on leaves us in silence.
 So far all this addressed to the man, and these are a man's complaints. But if through philosophy you have united what up to this moment has been separated, and if the beautiful is lovable, and is one thing and the same, as you have heard the poet say,note[Perhaps a reference to Theognis, Elegies, 16-17: "The beautiful is good, and if a thing's not beautiful, it isn't good."] in that case we shall no longer attribute your silence to disdain, but will share your philosopher's joy, and will exhort you to keep clear of meanness, so that by union with what is strongest in your own nature, you may unite what is strongest in ours. May you be such a man as this, O best of men, and thrice longed-for of brothers!