THE CHAIN OF UNIVERSES 149 



radiation of light and heat is kept up indefinitely. 

 But if energy is indestructible, as we believe it is, it 

 is clear that even in an infinite universe there must 

 be some circulation of it. The energy whose dissi- 

 pation we observe is, after all, the energy, not of our 

 world, but of the infra- world, which alone provides 

 us with light and radiant heat ; and that same world, 

 as we know from the phenomena of radio-activity, 

 has reserves of energy which are but rarely tapped, 

 and which may possibly in future be traced to the 

 radiant energy dissipated into space. 



The realisation of the infra- world and the supra- 

 world amounts to a vast extension of the scope of 

 the laws of nature. But, on the other hand, it 

 opposes a decided barrier to their indefinite simpli- 

 fication. It has been a favourite idea with biologists 

 that all vital phenomena can ultimately be reduced 

 to the configuration and motion of atoms. With 

 an almost pathetic faith, grotesquely out of keeping 

 with their boasted scepticism, they have for several 

 generations past been clinging to this dogma. The 

 chemist, that most practical of men of science, has 

 preferred to deal with phenomena as they appeared 

 to his senses and became amenable to his balance, 

 liiirotte, and thermometer. The physicist, working 

 on the very borderland of science, always in touch 

 with ul tin int. foundations, and surrounded by the 

 incomprehensible, has almost developed into a 

 mystic. He has shattered the atom, and is now 



