We know very little about Diogenes Laertius as a person. One recent hypothesis is that his surname refers to his birthplace (the city of Laerte in Caria or Cilicia), but other interpreters prefer to think – on the basis of a controversial indication in his text – that he was born (and lived) in Nicaea in Bithynia; it is also generally admitted on the basis of the scanty and mostly negative internal evidence that he lived and worked at the beginning of the third century AD: the last philosophers he mentions are Sextus Empiricus (active c. 190 AD) and his disciple Saturninus, and the most recent source he refers to is Favorinus of Arelate. This approximate date helps us appreciate the chapter he devotes to Pythagoras at the beginning of Book 8 of his Lives (as I shall abbreviate the work known as Lives and Opinions of Eminent Philosophers), for it allows us to relate Diogenes’ treatment of Pythagoras to two philosophical movements deeply indebted to Pythagoreanism, i.e. Neopythagoreanism and Neoplatonism.
