OF KNOWLEDGE. 401 



Faraday by the British mathematicians of the Cambridge 

 school, and by the introduction of the conception of 

 energy and the theory of its distribution in the plenum 

 of space. In passing, it may be remarked that an 

 absolute plenum and perfect contact present as much 

 difficulty to the thinking mind as action at a distance 

 does, but this does not prevent these conceptions being 

 of great use as soon as they can be mathematically 

 defined. 



But this change in the fundamental notions with 

 which the new school of natural philosophers, headed by 

 Faraday, worked, not only proved extremely fruitful by 

 opening out new vistas of research and avenues of 

 thought leading to the discovery of many quite un- 

 expected facts ; it had also the philosophically far more 

 important effect of shaking the confidence with which 

 the popular mind regarded, not the results, but the pro- 

 cesses and contrivances, of mathematical and mechanical 

 reasoning. This was still more the case when it became 

 increasingly difficult to construct mechanical models of 

 those elementary motions and mechanisms through 

 which the mathematician pictured to himself the funda- 

 mental processes of nature. The construction of such 

 models, though only mentally, seems to the present day 

 to be a desideratum for some of the greatest minds as 

 often as they attempt to give mechanical explanations. 

 But as these models grew more and more complicated, 

 the conviction gradually dawned upon philosophical 

 thinkers that such devices could no longer be considered 

 as describing the real processes of nature, but that they 

 were merely convenient and helpful means by which 



VOL. in. 2 c 



