green leaves." Darwin's Century (1958) This book's subtitle is, "Evolution and the Men Who Discovered It." Eiseley documented that animal variation, extinction, and a lengthy history of the earth were observed from the 1600s onward. Scientists groped towards a theory with increasingly detailed observations. They became aware that evolution had occurred without knowing how. Evolution was "in the air" and part of the intellectual discourse both before and after On the Origin of Species was published. The publisher describes it thus: At the heart of the account is Charles Darwin, but the story neither begins nor ends with him. Starting with the seventeenth-century notion of the Great Chain of Being, Dr. Eiseley traces the achievements and discoveries of men in many fields of science who paved the way for Darwin; and the book concludes with an extensive discussion of the ways in which Darwin's work has been challenged, improved upon, and occasionally refuted during the past hundred years. Persons whose contributions are discussed include Sir Thomas Browne, Sir Francis Bacon, Carl Linnaeus, Benoît de Maillet, the Comte de Buffon, Erasmus Darwin, Louis Agassiz, Jean-Baptiste Lamarck, James Hutton, William Smith, Georges Cuvier, Étienne Geoffroy Saint-Hilaire, Sir Charles Lyell, Thomas Robert Malthus, William Wells, Patrick Matthew, Karl von Baer, Robert Chambers, Thomas Henry Huxley, Sir John Richardson, Alexander Humboldt, Gregor Mendel, Hugo De Vries, W. L. Johannsen, Lambert Quételet, and Alfred Russel Wallace. Critics discussed include Fleeming Jenkin, A.W. Bennett, Lord Kelvin, and Adam Sedgwick, both a mentor and a critic. According to naturalist author Mary Ellen Pitts, in the "seminal" Darwin's Century, Eiseley was studying the history of evolutionary thinking, and he came to see that "as a result of scientific studies, nature has become externalized, particularized, mechanized, separated from the human and fragmented, reduced to conflict without consideration of cooperation, confined to reductionist and positivist study." The results for humankind, "as part of the 'biota' – Eiseley's concern as a writer – are far reaching." In the book, his unique impact as a thinker and a literary figure emerges as he reexamines science and the way man understands science. She concludes that, for Eiseley, "Nature emerges as a metonym for a view of the physical world, of the 'biota,' and of humankind that must be reexamined if life is to survive." In his conclusion, Eiseley quotes Darwin: "If we choose to let conjecture run wild, then animals, our fellow brethren