that already by Aristotle's time the early Ionians were largely names only to which popular tradition attached various ideas or achievements with greater or less plausibility". He points out that works confirmed to have existed in the sixth century BC by Anaximander and Xenophanes had already disappeared by the fourth century BC, so the chances of Pre-Socratic material surviving to the age of Aristotle is almost nil (even less likely for Aristotle's pupils Theophrastus and Eudemus and less likely still for those following after them). Diogenes Laërtius The main secondary source concerning the details of Thales' life and career is Diogenes Laërtius, "Lives of Eminent Philosophers". This is primarily a biographical work, as the name indicates. Compared to Aristotle, Diogenes is not much of a philosopher. He is the one who, in the Prologue to that work, is responsible for the division of the early philosophers into "Ionian" and "Italian", but he places the Academics in the Ionian school and otherwise evidences considerable disarray and contradiction, especially in the long section on forerunners of the "Ionian School". Diogenes quotes two letters attributed to Thales, but Diogenes wrote some eight centuries after Thales' death and that his sources often contained "unreliable or even fabricated information", hence the concern for separating fact from legend in accounts of Thales. It is due to this use of hearsay and a lack of citing original sources that leads some historians, like Dicks and Werner Jaeger, to look at the late origin of the traditional picture of Pre-Socratic philosophy and view the whole idea as a construct from a later age, "the whole picture that has come down to us of the history of early philosophy was fashioned during the two or three generations from Plato to the immediate pupils of Aristotle". See also Know thyself Material monism Plato's Academy mosaic Notes References (1991 pbk ed. ; 2011 3rd edition) Third Edition Herodotus, Histories, A. D. Godley (translator), Cambridge: Harvard University Press, 1920; . Online version at Perseus Hans Joachim Störig, Kleine Weltgeschichte der Philosophie. Fischer, Frankfurt/M. 2004, . Pliny the Elder, The Natural History (eds. John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A.) London. Taylor and Francis. (1855). Online version at the Perseus Digital Library. Further reading Priou, Alex (2016). "The Origin and Foundations of Milesian Thought." The Review of Metaphysics 70, 3–31. External links Thales of Miletus from The Internet Encyclopedia of Philosophy Thales