[“Homer was an astronomer”] (Kahn 23, D105)
[“Thales practiced astronomy.”] (Kahn 24, D38)
I put these two fragments together. Both are statements of importance to historians as they reconstruct views of developments in astronomy in Greece. The statement on Homer comes from Scholia on Iliad (XVIII.251). The statement on Thales is from Diogenes Laertius. The broader passage of the later quote is “According to some sources, Thales seems to have been the first to practice astronomy and predict solar eclipses and solstices…Heracliltus also bears witness to him” (Kahn p. 112).
As Kahn notes, the authenticity of the statement about Homer has been questioned because the contexts of the scholiasts’ report indicate that they mean to speak to astology; and there is no evidence of astrology in Greece previous to Heraclitus.
The current view of historians is that the Illiad and the Odyssey were likely written by one main author. However, Milman Parry in particular helped establish the view that the works were part of a longer oral tradition. A difficulty in drawing on such texts for accurate historic record of astrology or some other areas is that any of those who contributed over time, or Homer himself, might have changed elements like the dates of events, such at the seige of Troy. Scholars tend to think that some written document existed by the 7th century BCE, and was used by the Homeridae and rhapsodes, the professional reciters. All of this makes it especially difficult to establish what Homer might have known about astronomy. It has been suggested by some that Heraclitus may be speaking facetiously of Homer here, as he does elsewhere, here perhaps indicating that Homer had his head in the clouds. But there appears to be no good reason to read his similar statement about Thales facetiously.
Thales is clearly known as having had knowledge of astronomy. Heraclitus’ fragment is just one of the early statements pointing this out. Heroditus is one of the earliest sources indicating that Thales successfully predicted an early solar eclipse (Hdt. I.74) on 28 May 525 BCE. Numerous ancient writers also indicate this. Diogenes Liertius indicates that Thales was the first predict the course from solstace to solstace (Diogenes Laertius I.24) He may have gotten the view that the year is 365 days from the Egyptians. Diogenese Laertius also indicates that he calculated the orbit of the moon. Thales is also attributed with having been the first to highlight the advantages of sailing using Ursa Minor rather than Ursa Major (For an overview of some of this, see Patricia O’Grady’s “Thales of Miletus,” Internet Encyclopedia of Philosophy).
While Heraclitus did not think Thales and the other Ionian natural philosophers had much philosophical sophistication, he did not totally depreciate them.