92 THE KIDDLE OF THE UNIVERSE. 



The soul, on the other hand, is an immortal, imma- 

 terial being, a spiritual agent, whose mysterious activity 

 is entirely incomprehensible to us. This trivial con- 

 ception is, by its very terms, spiritualistic, and its 

 contradictory is, in a certain sense, materialistic. It 

 is, at the same time, supernatural and transcendental, 

 since it affirms the existence of forces which can exist 

 and operate without a material basis ; it rests on the 

 assumption that outside of and beyond nature there 

 is a " spiritual," immaterial world, of which we have 

 no experience, and of which we can learn nothing by 

 natural means. 



This hypothetical " spirit world," which is supposed 

 to be entirely independent of the material universe, 

 and on the assumption of which the whole artificial 

 structure of the dualistic system is based, is purely a 

 product of poetic imagination ; the same must be said 

 of the parallel belief in the " immortality of the 

 soul," the scientific impossibility of which we must 

 prove more fully later on (chap. xi.). If the beliefs 

 which prevail in these credulous circles had a sound 

 foundation, the phenomena they relate to could not be 

 subject to the ''law of substance"; moreover, this 

 single exception to the highest law of the cosmos 

 must have appeared very late in the history of the 

 organic world, since it only concerns the " soul " of 

 man and of the higher animals. The dogma of " free 

 will," another essential element of the dualistic psy- 

 chology, is similarly irreconcilable with the universal 

 law of substance. 



Our own naturalistic conception of the psychic 

 activity sees in it a group of vital phenomena, which 

 are dependent on a definite material substratum, like 

 all other phenomena. We shall give to this material 



