Socrates

Socrates was a Athenian (classic Greek) philosopher credited as one of the founders of Western philosophy, and as being the first moral philosopher, of the Western ethical tradition of thought. A mysterious figure, he has written nothing, and is known chiefly through the accounts of classical writers writing after his lifetime, particularly his students Plato and Xenophon. Other sources of his existence include the contemporaneous Antisthenes, Aristippus, and Aeschines of Sphettos. Aristophanes, a playwright, is the only source to have written during his lifetime.

Sources/Citations
https://en.wikipedia.org/wiki/Socrates