Antisthenes

Antisthenes (; Ancient Greek: Ἀντισθένης, pronounced [an.tis.tʰén.ε:s]; c. 446 – c. 366 BCE) was a Greek philosopher and a pupil of Socrates. Antisthenes first learned rhetoric under Gorgias before becoming an ardent disciple of Socrates. He adopted and developed the ethical side of Socrates' teachings, advocating an ascetic life lived in accordance with virtue. Later writers regarded him as the founder of Cynic philosophy.

Source: Wikipedia — https://en.wikipedia.org/wiki/Antisthenes