/O SCEPTICISM. 



actual solidity of bodies. The latter is due to re- 

 pellent forces acting at molecular distances, and not 

 due to contact with the atoms. Nor is it even true 

 that the complex of interacting atoms composing a 

 body is solid in the way the body seems to be solid, 

 seeing that the atoms are separated by distances 

 vast when compared with their own size.* And as 

 nothing else can come within striking distance of 

 them and put their internal economy to the test, it 

 is difficult to see what it matters whether the atoms 

 are solid or liquid, empty or full inside. 



It follows from the atomic theory in its present 

 shape that the solidity which we feel is not real, 

 that the solidity which exists is not relevant, and 

 that bodies are not really solid. And the atomic 

 theory is not only false, but feeble. It cannot, after 

 all, explain the behaviour of bodies, but must call to 

 aid the hypothesis of a luminiferous ether, inter- 

 penetrating all bodies, the vibrations of which are 

 supposed to explain the phenomena of light. The 

 qualities of this ether are so extraordinary that not 

 even the boldest scientists venture to determine 

 them all, such as whether it is continuous or atomic. 

 Nor is this reluctance without good reason. For If 

 the ether is continuous, it cannot vibrate ; while if it 

 is atomic, there miast exist voids between its inter- 

 stices, and all physical action must in the last resort 

 be action at a distance. The first alternative, of a 

 vibrating ether which cannot vibrate, is too obviously 

 absurd to be explicitly stated, while the second would 

 outrage one of the most cherished of the anthropo- 

 morphic prejudices of science. Still, the avowed 



^ As the size of the interstices in the most solid bodies is to 

 that of the atoms as five to one, it is clear that the solidity we 

 feel has not much to do with the hardness of the atoms. 



