Thales of Miletus

Influenced by Babylonian astronomy & Ancient Egyptian mathematics and religion

Influenced: Pythagoras, Anaximander (student of Thales), Anaximenes

Thales of Miletus (c. 624 BC – c. 546 BC, ~78 years old, lived during the Archaic period (c. 750 – c. 500 BC)) was a pre-Socratic Greek philosopher from Miletus, Ionia in Asia Minor (modern west coast turkey)

• Known as the Father of Western (and Greek) Philosophy as he gave a naturalistic explanation of the cosmos and supported it with reasons.
• One of the Seven Sages of Greece
• Attempted to explain natural phenomena rationally without reference to mythology, he was an original thinker
• None of his writings have survived
• He was the first to ask the question: What is the basic nature of reality?
• Material Monism - all of the world's objects (or universe) are composed of a single element (the source of everything), which for Thales was water, the first principle, the primary substance
• Made important contributions to:
  • Mathematics, particularly Geometry (as he introduced it to Greece from Egypt): Thales' theorem, Intercept theorem
  • Astronomy: prediction of a solar eclipse, determined the dates of the solstices, the diameters of the sun and moon, described the seasons, and discovered Ursa Minor.
  • Earth: the cause of earthquakes, and the Earth floats on water, possibly worked out the Earth is spherical. 
• He is credited with the first use of deductive reasoning applied to geometry, by deriving four corollaries to Thales' Theorem