Observe your enemies, for they first find out your faults.

Physics
His work on Natural Philosophy (the Physicus) contained a theory of the nature of the gods in which he argued that there were many gods believed in by the people but only one natural God. To one asking what sort of woman to marry - "If Antisthenes's beautiful you'll not have her to yourself; if Antisthenes's ugly you'll pay for it dearly. His favourite style seems to have been dialogues some of them being vehement attacks on his contemporaries as on Alcibiades in the second of his two works entitled Cyrus on Gorgias in his Archelaus and on Plato in his Satho.

Antisthenes first learned rhetoric under Gorgias before becoming an ardent disciple of Socrates. Antisthenes (Greek: Ἀντισθένης; c. He adopted and developed the ethical side of Socrates' teachings advocating an ascetic life lived in accordance with virtue.