Charles Robert Darwin, the British biologist whose theory of organic evolution revolutionized science, philosophy, and theology, was born at Shrewsbury. He attended the universities of Edinburgh and Cambridge but was not attracted by his medical studies at the first or by his theological studies at the second. Near the end of his undergraduate days he formed a friendship with J. T. Henslow, professor of botany at Cambridge, "a man who knew every branch of science" (Autobiography of Charles Darwin). This association, together with an enthusiasm for collecting beetles and a reading of works by Wilhelm von Humboldt and John Herschel, generated in him "a burning zeal to contribute to the noble structure of Natural Science." The opportunity to do so on a large scale arose when Henslow secured for him the post of naturalist "without pay" aboard the H.M.S. Beagle...