Thales of Miletus

Philosopher and scientist; b. c. 624 BC, d. c. 548 - 545 BC

Not much is known about the details of Thales' life. He did not leave any written documents; it is likely that he did not write anything at all.

According to the Greek historian Diogenes Laërtius of the 3rd century AD, who quotes 2nd century BC Apollodorus of Athens, Thales was born during the 39th Olympiad (c. 624 BC; the transcription of Diogenes' manuscript gives the 35th Olympiad, which is apparently an error) and died in the 58th Olympiad (548-545 BC) at the age of 78. He was of Phoenician descent and thus could bring much astronomical knowledge to the Greek civilization.

It is evident that Thales was held in high esteem already in antiquity. Many quotes and episodes relate to him, some clearly impossible to be true. The most impressive claim is told by Xenophanes of Colophon, who claimed that Thales predicted the solar eclipse of 28 May 585 BC. That the eclipse occurred and that it was a total eclipse is beyond doubt; it stopped the battle between King Alyattes of Lydia and King Cyaxares of Media and frightened the troops to such an extent that a peace could be negotiated But Greek astronomy was incapable of calculating eclipses to such accuracy, and the story is just an illustration of Thales' reputation as an astronomer.

Thales is reported to have measured the Egyptian pyramids and to calculate the distance from shore of ships at sea, using his advanced geometry.

Aristotle reported that Thales was the first to suggest that the universe is made up of a single matter and than this matter is water, or more accurately moisture, which in its various phases can turn into air, earth, and if further compressed into fire. The choice of water as the single building block is of less importance than Thales' attempt to reduce many phenomena to a common cause. This is evident from commentaries of later philosophers:

• "For there must be some natural substance, either one or more than one, from which the other things come into being, while it is preserved. Over the number, however, and the form of this kind of principle they do not all agree; but Thales, the founder of this type of philosophy, says that it is water." (Aristotle Metaf. A3,983b6) (1)
• "Others says that the earth rests on water. For this is the most ancient account we have received, which they say was given by Thales the Milesian, that it stays in place through floating like a log or some other such thing (for none of these rests by nature on air, but on water) - as though the same argument did not apply to the water supporting the earth as to the earth itself." (Aristotle On Soul) (1)
• "For moist natural substance, since it is easily formed into each different thing, is accustomed to undergo very various changes: that part of it which is exhaled is made into air, and the finest part is kindled from air into aither, while when water is compacted and changes into slime it becomes earth. Therefore Thales declared the water, of the four elements, was the most active, as it were, as a cause." (Heraclitus Homericus Quaest. Hom. 22) (1)
• "For he [Thales] said that the world is held up by water and rides like a ship, and when it is said to 'quake' it is actually rocking because of the water's movement." (Seneca Qu. nat. III, 14) (1)

The Greek gods had no place in Thales' cosmology. His personal religious beliefs are of course not known, but whatever they were, Thales kept them separate from his philosophy of the physical world. There is some indication that he believed in a soul not only in humans but also in other parts of the universe:

• "Thales, too, to judge from what is recorded of his views, seems to suppose that the soul is in a sense the cause of movement, since he says that a stone [magnet, or lodestone] has a soul because it causes movement to iron' (De An. 405 a20-22); 'Some think that the soul pervades the whole universe, whence perhaps came Thales' view that everything is full of gods." (De An. 411 a7-8) (Aristotle) (2)

References

1. G.S.Kirk, J.E.Raven,M.Schofield., 'The Presocratic Philosophers', A Critical History with a selection of texts, Second Edition, Cambridge University Press [1995]

2. Patricia.OGrady Flinders University,
http://www.utm.edu/research/iep/t/thales.htm

Photo: public domain (Wikipedia)

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