250 THE RIDDLE OF THE UNIVERSE. 



of time and space has become a prolific source of 

 error. It overlooks the fact that Kant only touched 

 one side of the problem, the subjective side, in that 

 theory, and recognised the equal validity of its 

 objective side. "Time and space," he said, "have 

 empirical reality, but transcendental ideality." Our 

 modern monism is quite compatible with this thesis 

 of Kant's, but not with the one-sided exaggeration of 

 the subjective aspect of the problem ; the latter leads 

 logically to the absurd idealism that culminates in 

 Berkeley's thesis, "Bodies are but ideas; their 

 essence is in their perception." The thesis should be 

 read thus : " Bodies are only ideas for my personal 

 consciousness ; their existence is just as real as that 

 of my organs of thought, the ganglionic cells in the 

 grey bed of my brain, which receive the impress of 

 bodies on my sense organs and form those ideas by 

 association of the impressions." It is just as easy to 

 doubt or to deny the reality of my own consciousness 

 as to doubt that of time and space. In the delirium 

 of fever, in hallucinations, in dreams, and in double- 

 consciousness, I take ideas to be true which are 

 merely fancies. I mistake my own personality for 

 another (vide p. 189) ; Descartes's famous Cogito ergo 

 sum applies no longer. On the other hand, the 

 reality of time and space is now fully established 

 by that expansion of our philosophy which we owe 

 to the law of substance and to our monistic cosmo- 

 gony. When we have happily got rid of the unten- 

 able idea of " empty space," there remains as the 

 infinite "space-filling" medium matter, in its two 

 forms of ether and mass. So also we find a " time- 

 filling" event in the eternal movement, or genetic 

 energy, which reveals itself in the uninterrupted 



