Thales of Miletus
Life and Work
Thales of Miletus (fl. c. 585 BC) is regarded as the father of philosophy. He is also considered the founder of Milesian school and one of the seven sages. Only few fragmentary sources survive from Thalesí work. Some ancient authors ascribe to him, without serious justification, a work with the name Nautical Star-guide while according to some others he wrote only two works: On the Solstice and On the Equinox.
Astronomy and Mathematics
Thales was also a great astronomer and mathematician. It is significant that he foretold the eclipse of the sun in 585 BC. Thales was an avid traveler. Herodotus provides important evidence for Thalesí activities as statesman and engineer. He seem to measure the pyramids of Egypt by their shadow, having observed the time when our shadow is equal to his height. As a mathematician, Thales is famous for his theorems, three of which are attributed to him by Proclus: circle bisected by diameter; angles at base of isosceles triangle are equal vertically opposed angles are equal.
Thales was the first Greek philosopher to speculate about the primary material element or source (arche) of all beings and cosmic phenomena, which he identified as water (hydor). The importance of water in life and nature was probably the principal reason that made Thales came to this conclusion. According to another viewpoint, Thales probably follows the traditional Homeric world-image and more precisely that of Oceanos; the river source of all mortal and immortal life. On this basis, Thales states that the earth floats on water like a raft.
Thalesí monistic view of water leads him to animistic pantheism. Since water is the divine source of all living things and so all animate and inanimate things can be alive, then the whole world is full of gods. This conclusion leads Thales to suggest that the real substance of soul and nature is water since waterís power is fundamentally kinetic.
De Anima IIa7
Translation M. R. Wright