Letter 714
To Celsus, governor of Cilicia. (362)
You know this Diogenes as one of our citizens. But that is not all he is to us -- he once endured a trial comparable to that of Zopyrus [the Persian who mutilated himself to gain the enemy's trust and take Babylon for Darius].
Do not look down on the wars that sophists wage, or on the young men who distinguish themselves in them -- Diogenes here is one of those. We once decided to sting Acacius with a playful trick.
The trick was a staged student defection. We needed someone who could play the part brilliantly, and no one seemed better than Diogenes. He turned out to be even better than we expected. He was believed immediately. The flattering words came pouring in. He escorted Acacius to his carriage like a proper student, then leapt away at the door and ran back to our group, who were watching the whole thing like an audience at a play. And so, instead of Babylon, we had a reason to laugh -- even my uncle, who was there, could not help himself.
Consider, then, how you might repay his courage -- by helping him against a man who owes him money.
Modern English rendering for readability. See the 19th-century translation or original Latin/Greek for scholarly use.