"This intricate picture has not been easy to put together. It has required a succession of insights over three centuries, each one demanding a huge leap of imagination, and the Earth scientists, though little recognized, have been among the most imaginative of all. But because the insights did require such imagination, each has met with incredulity. No scientists have been more comprehensively scorned than those who have sought to explain how the world behaves. Time after time, however, the most extraordinary ideas have turned out to be right, and the conservative notions have proved inadequate."