In about 585 BCE, a man named Thales amazed his fellow Milesians by correctly predicting an eclipse of the sun. A few years earlier or later (the record is scanty and unclear), Thales also made a trip to Egypt, where he calculated the height of a pyramid by measuring the length of its shadow at the same time of day that his own shadow equaled his actual height.1 With these two feats, Thales signaled a major change in Greek thinking and world thinking. A new, rational way of understanding reality was born, as opposed to one tied to myth or religious ritual—as still prevailed in two much older
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