70 TWO THEORIES OF KNOWLEDGE 



definite quantity. The Energy of a body in 

 motion can be measured and stated in terms 

 of mass and velocity. 



The profound conception of Aristotle, under 

 which Nature was regarded as a potent Energy 

 containing within itself the capacity of generating 

 the phenomenal World, has again been revived and 

 realised but with great additions. The theory 

 in the hands of Science is now not only confirmed 

 by incessant experiment, but the relation which it 

 affirms between reality and phenomenon has been 

 quantified. 



Moreover, the actual operations under which the 

 potential generates the actual have, so to say, been 

 laid bare to view ; and lastly, the inter-transmuta- 

 bility of all forms of Energy and its real unity have 

 been established. 



The doctrine has therefore received a confirma- 

 tion of which Aristotle did not dream, and its 

 explanation has at the same time received an 

 illumination which his vague if profound adumbra- 

 tion could never afford. With this added support 

 the true conception of human knowledge has received 

 new strength. The theory is still, nevertheless, not 

 to be grasped without a resolute effort of reflection. 

 It involves an inversion of our everyday conceptions 

 more radical than that which was demanded by 



