Diogenes Laërtius
Diogenes Laertius ( /daɪˈɒdʒɨˌniːz leɪˈɜrʃəs/; Greek: Διογένης Λαέρτιος, Diogenēs Laertios; fl. c. 3rd century AD) was a biographer of the Greek philosophers. Nothing is known about his life, but his surviving Lives and Opinions of Eminent Philosophers is one of the principal surviving sources for the history of Greek philosophy.