On Diogenes Laertius’s Biography of Plato

Diogenes Laertius’s chapter on Plato comprises the entirety of Book III of the Lives. It is the second longest biography in the Lives (second only to Diogenes’s biography of Epicurus which concludes the text). In one notable section Diogenes addresses his scattered biography of Plato to an unnamed female patron.

Per Diogenes Laertius, Plato was an Athenian whose mother’s lineage could be traced to Solon, though Plato lived in the sixth generation from Solon. His true name was Aristocles, taken from his paternal grandfather. He was born around 429 BC. Interestingly enough Plato was rumored to share a birthday with the god Apollo. Plato had two brothers, Glaucon and Adeimantus (who both notably appear in Plato’s Republic) and he also had a sister Potone mother of Speusippus who was bequeathed the Academy upon Plato’s death.

Diogenes claims Plato got his nickname (“broad”) for his robust constitution when he studied gymnastics. Others claim the nickname from his style or his broad face. There is an old story that Socrates had a dream about a young swan that suddenly sprouted feathers and took flight. The next day he met Plato and he knew the young man was the physical representation of the swan. He studied Heraclitus and poetry before becoming a pupil of Socrates. After the death of Socrates Plato was drawn to Heraclitean and Parmenidean philosophy. He also traveled widely meeting with mathematicians and philosophers. When he returned to Athens he resided at the “Academy” or Hecademus so-named for an obscure Greek classical hero. Some say he participated in several military campaigns. He sailed to Sicily three times at the tyrant courts of Dion and Dionysus, and was very nearly either killed or enslaved in Sparta.

Per Diogenes: “He created a synthesis of the doctrines of Heraclitus, Pythagoras, and Socrates” (Book III.8). Diogenes also lists a variety of epitaphs inscribed on Plato’s tomb as well as a list of Plato’s students including Aristotle of Stagira.

Plato is said to have died either at age eighty-one or eighty-eight perhaps at a wedding feast in 380 BC.

Diogenes offers some insights into his interpretation of Platonic philosophy at the end of his biography. He says Plato was likely not the first to write dialogues (perhaps that was Zeno of Elea) however Diogenes suggests: “Of the Platonic dialogues there are two principal types, one adapted for instruction, the other for inquiry” (Book III.49). He discusses various ways in which the dialogues were organized in his day (none of which is foreign to us moderns). Having read a considerable number of the Platonic dialogues, I remain intrigued yet skeptical of dry claims to interpret Plato’s teaching without recourse to the narrative context of the dialogues.


For this reading I used the ‘Compact Edition’ of the Lives of the Eminent Philosophers by Diogenes Laertes translated by Pamela Mensch and edited by James Miller.

In the preface to the Compact Edition the editors note: “Our common goal has been to make Lives as accessible as possible to English-speaking readers -and at the same time to convey some of the essential strangeness of what philosophy once was, in hopes that readers may wonder anew at what philosophy might yet become” (xiii).

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