Rather than identifying the past by numerical years (i.e. “455 BC”) ancient historians tended to associate ancient Greek epochs with the ruling archon of Athens at the time. The Athenian maintained meticulous lists of archons that went back many centuries. In this way, Diogenes Laertius claims Thales, the first of the “Seven Sages,” lived during the archonship of Damasius in Athens (perhaps 581 or 582 BC).
In reading Diogenes Laertius’s biography of Thales (as well as his prologue to the text) I was a bit overwhelmed by the sheer number of antiquated texts I had never heard of -many of which are now lost- that indicate the voluminous writings that were once circulating in classical antiquity, including many biographical “Lives” texts.
According to Diogenes, Thales may have hailed from either Phoenicia or Miletus (the latter seems to be more widely accepted today). He was the first to be called a “Sage” and he received widespread praise from men like Herodotus and Xenophanes for his uncanny ability to map the stars (he was reputed to be an extraordinary astronomer). He was also reputed to be an astute advisor in matters of political affairs -he was employed by Croesus the Lydian. he traveled widely, including to Egypt in order to learn from the Egyptian priests.
According to Diogenes: “He held that the original substance of all things is water, and that the world is animate and full of deities. They say he discovered the seasons of the year, and divided the year into 365 days” (Book I. 27).

Diogenes lists various oracular prophecies made in relation to Thales as well as ancient song (translated from earlier Greek writers like Lobon of Argos):
“Numerous words do not express a sound opinion.
Seek for one thing only: that which is wise.
Choose one thing only: that which has merit.
For you will check the tongues of men whose chatter never ceases” (Book I. 35)
Per Diogenes, various maxims were attributed to Thales during and after his lifetime (of course Diogenes was writing his book many centuries Thales’s death) and in the text Diogenes includes two brief letters from Thales. Much of the reputation of Thales seems to come from his maxims, his quiet demeanor, his wisdom in political affairs as well as his knowledge of the natural world, particularly astronomy, his respect for the divine, and his capacity to posit creative unifying theories about the nature of things. Thales was reported not to fear death and he died at the age of seventy-eight due to heat and thirst while attending an athletic competition. Diogenes rather dubiously claims it was Thales, not Phemonoe the mythological first priestess of the oracle at Delphi, who authored the famous maxim “Know Thyself” which was carved onto the wall of the temple of Apollo.
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).