Thales was the first man to have seen the cause of, and to predict, an eclipse of the sun. This means he figured out that the heavens move in regular ways that accord with mathematical reasoning. He was able to reason from visible effects to invisible causes and speculate about the intelligible order of nature as a whole. ... This moment contains many elements: satisfaction at having solved a problem; pleasure in using his faculties; fullness of pride, more complete than that of any conqueror, for he surveys and possesses all; certitude drawn from within himself, requiring no authorities; self-sufficiency, not depending, for the fulfillment of what is highest in himself, on other men or opinions or on accidents such as birth or election to power, on anything that can be taken from him; a happiness that has no admixture of illusion.