Macrobius, Saturnalia 1.11.42-44
“Diogenes the Cynic, although born free, had once been sold into slavery. When Xeniades the Corinthian had a mind to purchase Diogenes and asked him what skill he knew, Diogenes responded, ‘I know how to command free men.’ Xeniades was amazed at this response, so he purchased Diogenes, freed him, and entrusting his sons to him said, ‘Here are my sons for you to command.’”
Diogenes etiam Cynicus, licet ex libertate in servitutem venum ierat. 43 Quem cum emere vellet Xeniades Corinthius et, quid artificii novisset, percontatus esset: Novi, inquit Diogenes, hominibus liberis imperare. Tunc Xeniades responsum eius demiratus emisit manu, filiosque suos ei tradens: 44 Accipe, inquit, liberos meos quibus imperes.