WITH THE DOMAIN OF THE INORGANIC 65 



is possible to formulate a very large part at any rate of 

 what is observed in the inorganic domain. ^Yhether they 

 exhaust the reality of that domain is quite another ques- 

 tion. 



In both worlds we get the impression of order and uni- 

 formity. We recognise it, for instance, in the frequent in- 

 exorableness of the hereditary relation between successive 

 generations; we are even more familiar with it in the 

 domain of the inorganic. There do not seem to be many 

 big collisions in the heavens. Everything works so steadily 

 that the return of a comet can be predicted to a night, and 

 the occurrence of an eclipse to an hour. The weather may 

 be changeable, but no one supposes that it is disorderly. It 

 is not a multiverse that we live in, but a cosmos. In 

 his famous Discourse on Molecules (1873), Clerk-Maxwell 

 spoke of the verification of the postulate of stability in the 

 properties of things. Unthinkably distant worlds are built 

 up of molecules of the same kind as those which we find on 

 the earth. A molecule of hydrogen, for instance, whether 

 in our laboratories, or in Sirius or in Arcturus, executes 

 its vibrations in precisely the same time. The furniture 

 of the earth and of the heavens may be changed, but the 

 properties of its constituents remain. '^ Though in the course 

 of ages catastrophes have occurred and may yet occur 

 in the heavens, though ancient systems may be dissolved 

 and new systems evolved out of their ruins, the molecules 

 out of which these systems are built — the foundation-stones 

 of the material universe — remain unbroken and unworn. 

 They continue this day as they were created — perfect in 

 number arid measure and weight. ..." For ^' molecules '' 

 a modern chemist would read ^ atoms \ and even then he 

 would remind us of the apparent disintegration of the atom 



