Diogenes Laërtius

Diogenes Laërtius (Greek: Διογένης Λαέρτιος; fl. circa 3rd century AD) was a biographer of the Greek philosophers. Nothing is definitively known about his life, but his surviving Lives and Opinions of Eminent Philosophers is a principal source for the history of Greek philosophy. https://en.wikipedia.org/wiki/Diogenes_La%C3%ABrtius