Il6 THE CONCEPTION OF LIFE 



organism was working conscious oFIFs aim. How did this 

 vital teleology arise; how has it maintained itself? That 

 teleology is to be explained by the mechanistic theory is 

 again an assumption, the justification of which we still 

 await. 



Consciousness is the most obscure problem of biology. 

 Hitherto, the philosophers, and more recently, the psycholo- 

 gists, but not the biologists, have occupied themselves with 

 the study of consciousness, and they have, it seems, only got 

 so far that they can make it clear to us that consciousnes is 

 an ultimate conception, that is to say, a conception which 

 cannot be further analyzed. In an address, 60 which I delivered 

 in the year 1902, as President of the American Association 

 for the Advancement of Science, I endeavored to make clear 

 the importance of consciousness in the evolution of animals. 

 I adhere today to the opinion then expressed that the phylo- 

 genetic development, especially of vertebrates, was dominated 

 by the evolution of consciousness. If this is the case, it offers 

 an important proof of the great importance of consciousness 

 in animal life, and in fact we are forced to ascribe to conscious- 

 ness the leading role in evolution. It can have importance 

 only if it influences the life of animals. Consciousness is 

 active. In the address mentioned above I stated that accord- 

 ing to my conviction it is impossible to avoid the conclusion 

 that consciousness stands in immediate causal relation to 

 physiological processes. What is consciousness? There are 

 so far as I know only three possible explanations from 

 which we must choose. According to one view, consciousness 

 is not a real phenomenon, but a so-called epiphenomenon, 

 something that accompanies the physiological processes with- 

 out exerting any influence upon them. As a celebrated psy- 

 chologist expressed it to me, consciousness is merely the other 



