44 THE RIDDLE OF THE UNIVERSE. 



processes of life became, naturally, more conspicuous 

 as science advanced in the chemical and physical 

 explanation of the latter. The circulation of the blood 

 and a number of other phenomena could be traced to 

 machanical agencies ; respiration and digestion were 

 attributable to chemical processes like those we find 

 in inorganic nature. On the other hand, it seemed 

 impossible to do this with the wonderful performances 

 of the nerves and muscles, and with the characteristic 

 life of the mind ; the co-ordination of all the different 

 forces in the life of the individual seemed also beyond 

 such a mechanical interpretation. Hence there arose 

 a complete physiological dualism — an essential dis- 

 tinction was drawn between inorganic and organic 

 nature, between mechanical and vital processes, 

 between material force and life-force, between the 

 body and the soul. At the beginning of the nine- 

 teenth century this vitalism was firmly established in 

 France by Louis Dumas, and in Germany by Keil. 

 Alexander Humboldt had already published a poetical 

 presentation of it in 1795, in his narrative of the 

 Legend of Rhodes ; it is repeated, with critical notes, 

 in his Views of Nature. 



In the first half of the seventeenth century the 

 famous philosopher Descartes, starting from Harvey's 

 discovery of the circulation of the blood, put forward 

 the idea that the body of man, like that of other 

 animals, is merely an intricate machine, and that its 

 movements take place under the same mechanical 

 laws as the movements of an automaton of human 

 construction. It is true that Descartes, at the same 

 time, claimed for man the exclusive possession of a 

 perfectly independent, immaterial soul, and held that 

 its subjective experience, thought, was the only thing 



