186 THE RIDDLE OF THE UNIVERSE. 



oppose the dogmatism of the all-powerful secretary 

 and dictator of the Berlin Academy of Science. 



Towards the end, however, the author of the 

 " Ignorabimus speech " briefly alluded to the question 

 whether these two great " world-enigmas," the general 

 problem of substance and the special problem of con- 

 sciousness, are not two aspects of one and the same 

 problem. " This idea," he said, " is certainly the 

 simplest, and preferable to the one which makes the 

 world doubly incomprehensible. Such, however, is 

 the nature of things that even here we can obtain no 

 clear knowledge, and it is useless to speak further of 

 the question." The latter sentiment I have always 

 stoutly contested, and have endeavoured to prove that 

 the two great questions are not two distinct problems. 

 " The neurological problem of consciousness is but a 

 particular aspect of the all-pervading cosmological 

 problem of substance." 



The peculiar phenomenon of consciousness is not, 

 as du Bois-Reymond and the dualistic school would 

 have us believe, a completely "transcendental" 

 problem ; it is, as I showed thirty-three years ago, a 

 physiological problem, and, as such, must be reduced 

 to the phenomena of physics and chemistry. I sub- 

 sequently gave it the more definite title of a neuro- 

 logical problem, as I share the view that true con- 

 sciousness (thought and reason) is only present in 

 those higher animals which have a centralised nervous 

 system and organs of sense of a certain degree of 

 development. Those conditions are certainly found 

 in the higher vertebrates, especially in the placental 

 mammals, the class from which man has sprung. 

 The consciousness of the highest apes, dogs, elephants, 

 etc., differs from that of man in degree only, not in kind, 



