De Vi Physica 



necessary preliminary verification and scru- 

 tiny, any one should bring forward a principle 

 of explanation intrinsically impotent both in 

 kind and degree to effect the results in 

 question, it will not make matters any the 

 better, if he should subsequently ransack 

 heaven and earth in search of facts that only 

 seem to support it but never can : for no 

 amount of evidence can establish an impos- 

 sibility. It is futile to accumulate piles of 

 evidence to prove that two straight lines can 

 enclose a space. He ought to have begun 

 by testing the power and possibility, mathe- 

 matical or physical, of his principle, before 

 he set out. For to appeal to an adequately 

 powerful principle is truly scientific proce- 

 dure : to ascertain, with rigorous severity, 

 that it is adequate, before resorting to it, 

 is the mark of a really scientific thinker: 

 to explain power by impotence, supposed, by 

 reason of a want of analysis, to be potent, is 



