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Thales
Thales of Miletus [has been] since early antiquity regarded as the founder
of the Ionian school of natural philosophy. Evidence suggests that he was
a Milesian of Greek origin who flourished around 580 B.C. and that his
field of distinguished activities included practical and political matters. There
are indications that he visited Mesopotamia and Egypt, that he predicted
the possiblity of an eclipse in 585 B.C., and that he proposed a simple
doctrine on the origin and nature of the world.
The most ancient references to Thales depict him as a man of exceptional
wisdom. Later commentators associate him with specific discoveries in
physics, metaphysics, astronomy, geometry, and engineering. Modern
studies have hailed him as a proponent of the rational approach.
However, recent conservative reconstructions of Thales’ ideas have called
for the abandonment or modification of earlier estimates. In the absence of
primary sources, several scholars have argued that the earliest testimony
of Herodotus, Plato, and Aristotle must be preferred to later reports
stemming from the doxographic tradition. Such a preference is necessary,
they maintain, since Thales left no written documents, and most of the postAristotelian compilers depended for their comments on Aristotle’s reports.
When the ancient evidence is carefully examined, these commentators
hold, a believable picture of Thales’ thought emerges. The following is an
outline of his thought, based on the early sources.
Thales was very much concerned with the political conditions and
developments in Asia Minor during his time: as an advisor he showed
foresight in urging the Ionains to form a confederation against the
Persians. As a “learned person” (sophos) he showed remarkable vision,
correctly anticipating a solar eclipse during a battle between the Lydeans
and the Persians. As an engineer he made the Halys River passable for
King Croesus by diverting its waters.
In his speculations Thales asserted with unprecedented boldness that the
world originated in water and was sustained by water and that the earth
floated on water. Inasmuch as there is natural change everywhere, he
went on to claim, the world is animated, and even apparently inanimate
objects possess psyche, the principle of self-motion.
A fuller interpretation of the above necessarily takes one outside of the
historically confirmable; yet one must propose some interpretation beyond
the hard evidence if later fabrications are to be discarded. On the basis of
Aristotle’s cautious remarks it can be inferred that Thales thought of the
world as perfectly understandable through the idea of water - an element
essential to life (and thus to self-motion), versatile, common, and powerful
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enough to account for every physical phenomenon.
While there is very little elese that may be safely associated with Thales’ life
and thought, post-Aristotlelian commentators persist in crediting him with
many specific discoveries. They suggest that he discovered the solstices
and measured their cycles, that he discovered the five celestial zones
(arctic, antarctic, equator, and the tropics), the inclination of the zodiac, the
sources of the moon’s light, and more. He is said to have explained the
rise of the Nile as due to the etesian winds, and in geometry, to have
discovered proofs for the propositions that the circle is bisected by its
diameter, that the angles at the base of an isosceles triangle are equal, that
two triangles are identical when they have one side and the angles formed
by it with the other sides equal, and that in two intersecting straight lines
the opposite angles at the intersection are equal. He was supposedly
responsible for the axiomization of the field of geometry, and he was
further credited with measuring the height of the pyramids and the distance
of ships at sea.
Most of these unsubstantiated ascriptions must be judged as unhistorical
and inconsistent with the temper of the Milesian’s thought. Thales was the
last representative of a tradition that respected myth, was fond of intuitions,
and did not concern itself with proofs. To be sure, he was also the founder
of a new approach, that of attempting to comprehend the world through
reason alone.
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