Whereas Aristotle defended the appropriateness of slavery and Seneca derided only its cruelty, Dio Chrysostom vehemently opposed any argument in favor of keeping slaves. And he did it in the 1st Century CE Greco-Roman world, a society comfortable with slavery. This paper analyzes Dio’s dialogue _The Tenth Discourse: Diogenes or on Servants_ to try to understand how Cynics addressed the wrongs of slavery when so many other philosophers did not. The paper argues that Cynic commitments to self-sufficiency, freedom, and nature (...) helped them to recognize the immorality and injustice of owning slaves. And Dio’s work, which derided injustices that most others defended, shows that philosophers should resist excusing thinkers as mere products of their time, especially canonical figures such as Aristotle and Seneca. Not only were Aristotle and Seneca wrong, but so are contemporary philosophers if they do not hold such historical figures to account by acknowledging and discussing their limitations and faults as thinkers in relation to the historical circumstances they faced. (shrink)