THALES OF MILETUS Born in Miletus, on the Ionian coast of Asia Minor, Thales (c. 624-540 BC) was the first known Greek mathematician, the first Greek philosopher and one of the seven sages of antiquity. Breaking with mythological interpretations and believing that the world can be explained as a set of natural processes, he considered water, origin of all, in the spirit of natural philosophy that he pioneered. Thales excelled in cosmology, astronomy, physics and geometry. One of his best known contributions to mathematics is Thales’ theorem, or basic proportionality theorem. Thales was said to have calculated the height of the pyramids and predicted the solar eclipse of 585 BC. According to an anecdote, Thales fell into a well while stargazing. His importance as a thinker is enormous, as he was first in the long tradition of European philosophy and introduced the mathematical study of natural phenomena.