ON THE PHYSICAL VIEW OF NATURE. 187 



tion to it. It can be set out in the statement that 

 wherever energy shows itself it appears as composed of 

 two factors the intensity and the capacity factors. 

 These terms, borrowed from the older theories of heat 

 and electricity, measure the quantity of energy as well as 

 the direction in which changes of energy take place : the 

 general law being that energy, in whatever form it 

 may appear, tends to go from places of higher to places 

 of lower potential or intensity. 



The characteristic feature of this most recent outcome 52. 



The out- 



of the physical view of natural phenomena is that it come - 

 takes in real earnest the suggestion at which many 

 natural philosophers have independently arrived, that 

 energy is a substance quite as much as matter. This 

 granted, it seems at least reasonable to some thinkers to 

 see how far they can get by employing the two con- 

 ceptions of matter and energy alone without adopting 

 a third something, the ether, which was introduced at 

 a time when the idea of the conservation of energy 

 had not yet been formulated. 1 



1 For an indication of the further 

 development of this point of view I 

 must refer the reader to the chapter 

 on Photo - chemistry in Prof. Ost- 

 wald's great work ('Allg. Chemie,' 

 2nd ed., vol. ii. part 1, p. 1014, &c.) 

 "In the interest," he says, "of a 

 conception of nature which is free 

 from hypotheses, we must ask 

 whether the assumption of that 

 medium, the ether, is unavoidable. 

 To me it does not seem to be so. 

 If we ask for the cause of all dis- 

 placements of energy in space 

 which we can singly observe, we 



find that it always consists in differ- From this and other passages of 

 ences of intensity. . . . The main Prof. Ostwald's writings it seems 

 point ia that, having conceived as if mass likewise was to be given 



energy to be a real thing, indeed 

 the only real thing in the so-called 

 outer world, there is no need to 

 inquire for a carrier of it when we 

 find it anywhere. This enables us 

 to look upon radiant energy as in- 

 dependently existing in space. We 

 have found in the general law of 

 intensity i.e., in the empirical 

 fact that energy tends to equalise 

 forced changes of its density in 

 space the principle according to 

 which transmission of energy in 

 space necessarily takes place when 

 there appears anywhere an excess." 



