Looking down from the huge theatre and from the colonnade which lines The Sacred Way in Miletos this morning, my mind turned to the early philosophers of that city's Archaic Greek period. Several speculated on the stars, the planets and the Earth's relationship to them - the field of study that later evolved into astronomy.

Thales (7th century BCE) was the first. From secondary sources we know that he pictured the Earth as a disc floating in water, and covered by a hemispheric vault containing the stars.

Herodotos tells us the feat for which Thales is best known: predicting a "day-turning-to-night" event, undoubtedly a total eclipse of the sun. Apparently it occurred during a battle between the Medes and the Lydians, and caused both sides such consternation that they lay down their arms. Using modern eclipse knowledge we can place this event to 28 May 584 BCE - the earliest event in history that can be determined to a specific day.

Thales is hailed as one of the Seven Sages of antiquity. But Miletos also produced other philosophers noted for formulating theories of the cosmos. Anaximandros (c.611 to 545 BCE) proposed that the sun and moon were rotating wheels with hollow rims filled with fire. The fire was viewed through a circular aperture which, when obscured, produced an eclipse.

Anaximenes in the late 6th century BCE also speculated on how, and of what substances, the cosmos was constructed. The general view was that varying amounts of water, air and fire were its constituents, and that (in order of distance) the moon, sun and planets rose and set above the Earth within the vault of the fixed stars.

I find it adds a human dimension to think about the personalities who spent their lives in the sites we visit. As the history of astronomy and cosmology has been a particular interest of mine it's gratifying to have had the opportunity, perhaps literally, to walk in the steps of these great philosophers who were among the first to attempt to discover mankind's place in the cosmos.