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.
The addressee of this letter, Herculian, was a fellow-student of Synesius and an intimate friend. He also received letters 137, 138, 139, 145, 140, 141, 142, 146, and 144.
This letter is offered in the translation by A. Fitzgerald.
Letter 143: A Reproach
 To Herculian
You have not kept your promise, my dear friend, the promise which you made that you would not reveal those things which ought to remain hidden. I have just listened to people who have come from you. They remembered some of your expressions. and they begged me to reveal the meaning of them. But according to my custom I did not pretend to them that I understood the writings in question, nor did I say that I knew them.
 You no longer need any warning from me, my dear Herculian, for it would not be enough to convince you. Rather look up the letter which Lysis the Pythagorean addressed to Hipparchus, and when you have found it, oblige me by reading it frequently.note[According to a late tradition, Hipparchus - whose historicity is doubtful - had betrayed several secrets of Pythagoras.] Perhaps you will then experience a complete change of mind in regard to you uncalled-for revelation. "To explain philosophy to the mob," as Lysis says in his somewhat Dorian dialect, "is only to awaken amongst men a great contempt for things divine." How often have I met, time and time again, people who, because they had rashly listened to some stately little phrases, refused to believe themselves the laymen that they really were!
 Full of vanity, they sullied sacred dogmas by pretending to teach what they had never succeeded in learning. They attached to themselves three or four flatterers to flatter them, men in no way different in their souls from the vulgar, and none of them such as are instructed through early education. It is a dreadful thing and full of guile, this conceit of wisdom, shrinking at nothing in the case of the ignorant, and daring all things thoughtlessly; for what could be more reckless than ignorance?
 When I encounter such men, impostors, and drones, who are neither versed in letters nor set themselves to the task, I feel detestation for the tribe, but I can find no other cause for the state of their culture than this, that they have been injudiciously and prematurely deemed worthy at the start, no doubt by others such as themselves, to listen to the supremely valuable doctrines. For my part I am and advise you also to be, a more careful guard over the mysteries of philosophy. That these things are fitted for Herculian, I know well, but if you have approached philosophy itself sincerely, you ought to avoid the society of those who are not faithful to it, and who by their pretence adulterate its great sanctity.
 Now in the name of the God of friendship who watches over you, do not show my letter to certain people for, if you do so, these pictures of evil will anger those who recognize in themselves or amongst their friends the features recorded. To give pain is sometimes a manly act, and quite in the character of philosophy, but only when face to face with those concerned.
 It seems petty even to write about these things, but whatever Synesius says to himself, he says equally to your honored soul, to you, his only friend, or at least, his best friend, for he has two others besides. Outside of this triad that you form, there is nothing human that I honor. In joining myself to you I forthwith complete a quaternary of sacred friendship, but as to the nature of the like-named quaternary which belongs to first principles, let it be mentioned with reverence.
 In the four sets of iambics,note[See Letter 141.] I found at the end of twelve lines written continuously as if they only formed a single epigram. As it is quite possible that you have copies of these verses, know them that they are not one and the same, nor are they by one author. The first eight lines, written with knowledge of verse in which poetry is mingled with astronomy, are by your friend. The four last are merely poetic daintiness, and an ancient fragment. Now, in my opinion, it is much greater sacrilege to steal the verses of the dead than to steal their garments, a thing called grave-robbing.
 Take continual care of your health, seek after philosophy with religious care. I promise to wait for you, as long as the twentieth day of Mesori,note[13 August 402.] and then with God's help I shall take the road. Give all my regards to your excellent friend. I love him because he loves you greatly.