6 INTRODUCTORY NOTE 



arrived at entirely independently. On the advice of Lyell, the 

 geologist, and Hooker, the botanist, Wallace's paper and a letter 

 of Darivin's of the previous year, in ivhich he had outlined his 

 theory to Asa Gray, zvere read together on July I, 1858, and 

 published by the Linncean Society. In November of the follow- 

 ing year "The Origin of Species" was published, and the great 

 battle was begun between the old science and the new. This 

 work was followed in 1868 by his "Variation of Animals and 

 Plants under Domestication," that in turn by the "Descent of 

 Man" in i8yi, and that again by "The Expression of the Emo- 

 tions in Man and Animals." Each of these books was the elabo- 

 ration or complement of a section of its predecessor. The later 

 years of Darwin's life were chieAy devoted to botanical research, 

 and resulted in a series of treatises of the highest scientific value. 

 He died at Down on April ig, 1882, and is buried in Westminster 

 Abbey. 



The idea of the evolution of organisms, so far from originating 

 with Darwin, is a very old one. Glimpses of it appear in the 

 ancient Greek philosophers, especially Empedocles and Aristotle; 

 modern philosophy from Bacon onward shows an increasing 

 definiteness in its grasp of the conception; and in the age pre- 

 ceding Darivin's, Buffon, Erasmus Darwin, and Lamarck had 

 given it a fairly concrete expression. As we approach the date 

 of the publication of "The Origin of Species" adherence to the 

 doctrine not only by naturalists but by poets, such as Goethe, 

 becomes comparatively frequent; and in the six years before the 

 joint announcement of Darwin and Wallace, Herbert Spencer 

 had been supporting and applying it vigorously in the field of 

 psychology. 



To these partial anticipations, however, Darwin oiued little. 

 When he became interested in the problem, the doctrine of the 

 fixity of species was still generally held; and his solution occurred 

 to him mainly as the result of his own observation and thinking. 

 Speaking of the voyage of the "Beagle," he says, "On my return 

 home in the autumn of 1836 I immediately began to prepare my 

 journal for publication, and then saw how many facts indicated 

 the common descent of species. ... In July (1837) I opened 

 my first note-book for facts in relation to the Origin of Species, 

 about which I had long reflected, and never ceased working for 

 the next twenty years. . . . Had been greatly struck from about 



