304 THE PHILOSOPHY OF BIOLOGY 



were assemblages of molecules, molecules were assem- 

 blages of atoms, and the atoms themselves were either 

 simple or were composed of corpuscles, or still smaller 

 bodies. This mode of analysis was forced upon the 

 human mind by formal logic and geometry, and it was 

 apparently the only method of acquiring mastery over 

 nature. Yet there were difficulties, appreciated no less 

 by the philosophical physicists than by the writers on 

 formal philosophy. How could bodies, or molecules, 

 or atoms that were separated from each other act upon 

 each other ? The molecule A could only act upon the 

 molecule B if there were some particles between them 

 which could convey the impulse or attraction, but then 

 we must suppose that there were other particles between 

 these intermediate ones, and so on ad infinitum, other- 

 wise how could a body act, that is, really exist, where it 

 was not ? In other words, how could there be action 

 at a distance ? How, for instance, could the atoms 

 of the earth attract those of the moon with a force 

 sufficient to break a steel rope of 400 miles in diameter ? 

 Physics had therefore to invent the ether of space, not 

 only to account for interstellar or interplanetary gravi- 

 tation and other modes of radiant energy, but also to 

 account for the interaction of the atoms or molecules 

 which make up chemical compounds. In our own day 

 atoms have ceased to be the limits to the subdivision of 

 things : they are composed of electrons, but the elect- 

 rons are entities separated from each other by empty 

 space. They are not, however, the ultimate limits of 

 subdivision of matter, as the atoms were supposed to 

 be by the chemistry of the early part of the last century, 

 but are regarded as ' singularities ' in an universal 

 continuous medium or ether. It is of no moment 

 that we are unable to describe the ether in terms of 

 our former concepts of matter and energy, or at least 



