ferences between the ways in which he and Wallace formulated their ideas. In this essay, I argue that Darwin was truly original in his thinking, and I support this claim by addressing the related issue of defining just why the theory was so disturbing to his contemporaries. Darwin was certainly not the first to suggest the idea of evolution as an alternative to the creation of species by God. J. B. Lamarck’s theory, published in 1809, had been widely discussed,althoughgenerallyrejected(2–4).Robert Chambers’s Vestiges of the Natural History of Creation of 1844 sparked a debate over the possibility that new species were produced from