Diogenes Laërtius ( dy-OJ-in-eez lay-UR-shee-əs; Greek: Διογένης Λαέρτιος, Laertios; fl. 3rd century AD) was a biographer of the Greek philosophers. Little is definitively known about his life, but his surviving Lives and Opinions of Eminent Philosophers is a principal source for the history of ancient Greek philosophy. His reputation is...