Diogenes Laertius is the author of the only preserved example of an ancient "history of philosophy." The title of his book varies in surviving manuscripts but seems most likely to have been Compendium of the Lives and Opinions of Philosophers (circa third century A.D.). From the Renaissance until about 1800, this collection of biographies of philosophers was the principal model for the historiography of philosophy. In addition to his treatise, Diogenes composed a collection of poems; this work has been lost, but Diogenes quotes many of his poems in his Lives and Opinions.

Diogenes Laertius is known solely from his preserved book, and information about his life is virtually nonexistent. His date can be fixed only by the dates of the latest historic figures mentioned in his text (second century A.D.) and by the fact that he seems to have written before Neoplatonism became influential (circa A...