Nothing 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. 3rd century AD) was a biographer of the Greek philosophers. For other people named Diogenes, see Diogenes (disambiguation).ĭiogenes Laërtius ( / d aɪ ˌ ɒ dʒ ɪ n iː z l eɪ ˈ ɜːr ʃ i ə s/ dy- OJ-in-eez lay- UR-shee-əs Greek: Διογένης Λαέρτιος, Laertios fl.