SPENCER'S DEFENCE 283 



went on to maintain that, in the sense in which he understood it, d priori 

 intuition preceded experimental verification. 



He illustrated his meaning by deducing the second law of motion from 

 the d priori assumption that definite quantitative relations exist between cause 

 and effect. He evidently thought that " definite quantitative relations" meant 

 proportionality 1 . But whatever final meaning Spencer attached to the phrase 

 "& priori intuition," there was no getting away from the obvious meaning of 

 one of the passages quoted by the British Quarterly Reviewer : 



" Deeper than demonstration deeper even than definite cognition deep as the 

 very nature of mind is the postulate at which we have arrived (i.e. the Persistence 

 of Force). Its authority transcends all other whatever; for not only is it given in 

 the constitution of our own consciousness, but it is impossible to imagine a con- 

 sciousness so constituted as not to give it " (First Principles, p. 192). 



This was one of the stumbling blocks which Spencer out of consideration 

 for the future reader removed from his later editions. 



In reply to the criticism that the phrase Persistence of Force was used in 

 various quite distinct senses, Spencer remarked (Replies to Criticisms, p. 311) 

 that had " he (the Reviewer) not been in so great a hurry to find incon- 

 sistencies, he would have seen why, for the purposes of my argument, I 

 intentionally use the word Force : Force being the generic word, including 

 both that species known as Energy, and that species by which Matter 

 occupies space and maintains its integrity." 



This recalls Maxwell's metrical Report on Tait's Lecture on Force. 



That small word " Force," is made a barber's block, 



Ready to put on 

 Meanings most strange and various, fit to shock 



Pupils of Newton. 



But those whose statements baffle all attacks, 



Safe by evasion, 

 Whose definitions, like a nose of wax, 



Suit each occasion, etc. 



(See above, p. 254.) 



1 E.g., there is a definite quantitative relation between speed of projection and height reached, 

 between strength of electric current and heat generated ; but there is no simple proportionality. 

 The whole discussion in Nature (Vols. ix and x) is well worth reading. See especially the 

 British Quarterly Reviewer's letters on April 2, April 16, and June n. It is not an exaggeration 

 to say that in each succeeding letter Spencer takes up a different position, having been driven 

 from one after another of his fancied strongholds. The discussion was important as showing 

 to what extent Herbert Spencer's First Principles could be relied on as an exposition of physical 

 fact and theory. 



362 



