250 ESSAYS OF A BIOLOGIST 



quantitatively from each other, of electrical charges; 

 so that at the last all matter is one, and becomes per- 

 haps indistinguishable, or at least inseparable, from 

 energy. There is no personal operator for particular 

 happenings; the lightning and the volcano are the 

 inevitable outcome of the material constitution of 

 things, equally with the form and colour of a pebble 

 and with the fact that it will drop to the ground if it 

 is let fall. All is impersonal order and unity. 



There is, however, one other great fact about the 

 system of inorganic matter. The energy contained 

 in it tends to be degraded, as the physicists say — in 

 other words to become less readily available. There 

 is available energy in moving matter. There is po- 

 tential energy in all matter, dependent upon whether 

 it can be set in motion. But if the sea were to cover 

 the whole surface of the globe, it would be impossible 

 to extract energy from running water as we do now, 

 because no water would be running. So too heat is 

 energy; but it is only available when it can flow, 

 when there are hotter and colder bodies. The law 

 under which transformations of energy operate has 

 now been investigated, and it has been established 

 that in every energy-transaction a certain modicum 

 goes to waste as unavailable heat, so that, unless some 

 at present unforeseen change occurs, the last state of 

 the universe, considered as a purely physico-chemical 

 mechanism, will be one of death, of inactivity, with 

 all matter at a uniform low temperature and the 

 whole stock of energy locked up and unavailable 



