ARISTOTLE AS A BIOLOGIST 5 



of George Eliot and Lewes, Huxley, Tyndall, and many 

 more, found his place in the world of London. Hence- 

 forth, his life was so quiet, simple and retired, that we 

 might say of him, as Heine said of Kant, ' Er hatte weder 

 Leben noch Geschichte.' 



In 1855, in the Principles of Psychology , Spencer affirmed 

 his belief in the ' development hypothesis ',* as account- 

 ing for the origin of species ; and as accounting also for the 

 successive association of ideas, and so, by their becoming 

 ' innate ' and transmissible from generation to generation, 

 for the gradual development of mind: which latter 

 investigation, I need hardly say, has since been continued, 

 by a long line of evolutionary psychologists, in their 

 several and divergent ways. It is curious to learn from 

 his Autobiography that about this time, in his talks with 

 Huxley, it was the latter who still preserved a guarded 

 attitude, and Spencer who urged upon him, but with still 

 inadequate and unconvincing arguments, the hypothesis 

 of organic evolution. 



Five years later, a year after the publication of the 

 Origin of Species, Spencer brought out the prospectus 

 of his Synthetic Philosophy, that heroic effort to combine, 

 in a Philosophy of Evolution, the whole range of physical, 

 mental, and social science. To discover and trace that 

 one identical phenomenon of Evolution, in the progress 

 of civilization, in the development of mind, in the course 

 of nature, in the history of the Universe, was his single 

 and life-long aim. 



He found such tools as he worked with in the current 

 tendencies of political and economic thought, and in the 

 recent discoveries or generalizations of science. Of these 

 latter, on the physical side, the greatest was the principle 



1 As already, in 1852, he had done in his essay on the Development 

 Hypothesis. 



