75. Cleomenes in his work entitled Concerning Pedagogues says that the friends of Diogenes wanted to ransom him, whereupon he called them simpletons; for, said he, lions are not the slaves of those who feed them, but rather those who feed them are at the mercy of the lions: for fear is the mark of the slave, whereas wild beasts make men afraid of them. The man had in fact a wonderful gift of persuasion, so that he could easily vanquish anyone he liked in argument. At all events a certain Onesicritus of Aegina is said to have sent to Athens the one of his two sons named Androsthenes, and he having become a pupil of Diogenes stayed there; the father then sent the other also, the aforesaid Philiscus, who was the elder, in search of him; but Philiscus also was detained in the same way.
Source: The Lives and Opinions of Eminent Philosophers, by Diogenes Laertius, Literally translated by C.D. Yonge. London: Henry G. Bohn, 1853 | Life of Anacharsis only, Lives of the Eminent Philosophers by Diogenes Laërtius, translated by Robert Drew Hicks, Wikisource