Force, Energy, and Will 229 



Mr. Herbert Spencer as their speculative guide follow him in 

 seeking to express all existences of which we have or can 

 have any knowledge in terms of ' force ' — its persistence and 

 metamorphosis — as their only possible ultimate explanation. 

 Mr. Spencer himself has a chapter ^ on the transformation of 

 ' force/ Avherein he speaks of ' the transformation of heat into 

 electricity/ and of this latter, again, 'into other modes of 

 force ' ; he refers to Mr. Grove as having shown ' that each 

 force is transformable, directly or indirectly, into the others,' 

 and he himself brings even intellect and will within the 

 sphere of such transformations. Indeed he not only teaches 

 that force is a substance, but that it is the substance of 

 substances. He makes the persistence of force as ' an uncon- 

 ditioned reality ' ^ the most fundamental of all truths. 

 ' Deeper,' he tells us,^ ' than demonstration, deeper even than 

 definite cognition, deep as the very nature of mind, is the 

 postulate at which Ave have arrived. . . . The sole truth 

 which transcends experience by underlying it is the persist- 

 ence of force.' Here, then, Ave have a fundamentally dif- 

 ferent conception of 'force' from that Avhich Avas formerly 

 universal — the conception, in fact, of an actual multiform 

 substance instead of the conception of a property attached t© 

 substance, i.e. the activity of a substance. 



This change of conception has been brought about by the 

 brilliant discoveries of the quantitative equivalence which 

 exists betAveen the different successive activities of the same 

 or of different bodies, e.g. that quantitative equivalence 

 betAveen heat and motion Avhich has led Professor Tyndall 

 to speak of heat as ' a mode of motion.' The works of the 

 authors before referred to are replete Avith Avonderful ex- 

 amples of this quantitative equivalence betAveen many of the 

 activities Avhich bodies exhibit. 



1 First Principles, 3rd edition, chapter viii. - L. c, p. 189. 



^ L. c, p. 192. 



