OneHundred years ago, in July 1858, Darwin and Wallace propounded the theory of evolution by natural selection, and thereby caused a revolution in human thought. It may be of interest to recall that in certain important particulars, though not in all, this doctrine had been anticipated by the Greeks and Romans. Fragments of a striking didactic poem On Nature by the fifth-century philosopher, statesman, and mystic Empedokles of Akragas suggest a conception of nature as an experimenter, who by following a process of trial and error creates some strange monsters and mixtures of species. The more fantastic speculations of Empedokles were rejected by Epicurus, who reduced the idea to a more scientific form, and one more in conformity with the atomic theory; and the Epicurean version was in turn followed by Lucretius in the fifth book of the De Rerum Natura. The passages quoted below provide parallels to the ideas of natural selection and the survival of the fittest; but, as is now recognized, what Lucretius and the ancient world generally did not anticipate was the idea that crowned all—that natural selection could lead to the creation of new species by the evolution of one out of another. The relevant texts are cited by Bailey in his commentary on these passages.