As the illustrious Roman scholars Varro and Cicero reflect on the ethical turn in Greek philosophy, they rightly focus on Socrates, observing that he was the first to draw philosophy down from the heavens, placing her in the cities of men, so that she might inquire about life and morality. In the generation that follows Socrates, however, Diogenes of Sinope will unleash philosophy’s ethical potential with vitality and humour. Whereas Socrates identifies as a gadfly, Diogenes is a dog, and with him, ethics gains its bite.