n THE PKOGRESS OF SCIENCE 75 



reduction of the problems of the world of the in- 

 finitely little, as it already has reduced those of 

 the infinitely great world, to questions of me- 

 chanics. 1 



In the meanwhile, the primitive atomic theory, 

 which has served as the scaffolding for the edifice 

 of modern physics and chemistry, has been quietly 

 dismissed. I cannot discover that any contem- 

 porary physicist or chemist believes in the real in- 

 divisibility of atoms, or in an interatomic matterless 

 vacuum. The term " atoms " appears to be used 

 as a mere name for physico-chemical units which 

 have not yet been subdivided, and " molecules " 

 for physico-chemical units which are aggregates of 

 the former. And these individualised particles are 

 supposed to move in an endless ocean of a vastly 

 more subtle matter the ether. If this ether is 

 a continuous substance, therefore, we have got 

 back from the hypothesis f Dalton to that of 

 Descartes. But there is much reason to believe 

 that science is going to make a still further 

 journey, and, in form, if not altogether in substance, 

 to return to the point of view of Aristotle. 



The greater number of the so-called " elemen- 

 tary " bodies, now known, had been discovered 

 before the commencement of our epoch; and it 

 had become apparent that they were by no means 



1 In the preface to his Mecaniqiw Chimique, M. Berthelot 

 declares his object to be " ramener la chimie tout entiere . . . aux 

 memes principes mecaniques qui regisseut deja les diverses 

 branches de la physique. " 



