184 THE RIDDLE OF THE UNIVERSE. 



I cannot say. Since he considers consciousness to be 

 a transcendental phenomenon (as we shall see pre- 

 sently) , while denying that character to other psychic 

 functions — the action of the senses, for example — I 

 must infer that he recognises the difference of the 

 two ideas. Other parts of his eloquent speeches 

 contain quite the opposite view, for the famous orator 

 not infrequently contradicts himself on important 

 questions of principle. However, I repeat that, in 

 my opinion, consciousness is only part of the psychic 

 phenomena which we find in man and the higher 

 animals ; the great majority of them are uncon- 

 scious. 



However divergent are the different views as to the 

 nature and origin of consciousness, they may, never- 

 theless, on a clear and logical examination, all be 

 reduced to two fundamental theories — the transcen- 

 dental (or dualistic) and the physiological (or monistic) . 

 I have myself always held the latter view, in the light 

 of my evolutionary principles, and it is now shared 

 by a great number of distinguished scientists, though 

 it is by no means generally accepted. The transcen- 

 dental theory is the older and much more common ; 

 it has recently come once more into prominence, 

 principally through du Bois-Eeymond, and it has 

 acquired a great importance in modern discussions 

 of cosmic problems through his famous ' ' Ignorabimus 

 speech." On account of the extreme importance of 

 this fundamental question we must touch briefly on 

 its main features. 



In the celebrated discourse on " The Limits of 

 Natural Science," which E. du Bois-Keymond gave 

 on August 14th, 1872, at the Scientific Congress at 

 Leipzig, he spoke of two "absolute limits" to our 



