60 THE LIMITATIONS OF SCIENCE 



everything acts as if it existed [?] and that this 

 hypothesis is convenient in explaining phenomena. 

 After all, have we any other reason for believing in the 

 existence of material objects? Is not that belief also 

 a convenient hypothesis; only we shall never cease to 

 make it, meanwhile the time will come, without doubt, 

 when the ether will be rejected as useless." Both ma- 

 terial objects and the ether may be only hypotheses, or 

 rather our knowledge of them is relative, but not in 

 the same way; the existence of material objects is 

 based on direct experience and the existence of the 

 ether is not. However we may argue, the objective 

 reality of matter is a necessary idea, fixed in our minds 

 and not to be dislodged. 



Criticism is now often directed against the older 

 atomic theory because a given form of it no longer 

 accords with phenomena which have been lately dis- 

 covered. And it should be borne in mind that this new 

 theory of electrons has been developed with the main 

 purpose of supporting the atomic theory and making it 

 agree with our new knowledge of electricity. Thus 

 Professor Rutherford has recently performed a beau- 

 tiful experiment by which he detects electrically a por- 

 tion of helium gas, which he calculates to be of the 

 dimensions of a chemical atom. Here, he says, we 

 have at last an actual experimental proof of the reality 

 of the chemical atom. Does not this experiment show 

 just the reverse? The idea underlying all atomic 



