Notices respecting New Books. 401 



arid able to draw inferences, or, at least, " to represent a mind 

 endowed with powers of thought but wholly devoid of knowledge" 

 (vol. i. p. 127). This, however, would be to give a very inadequate 

 notion of the contents of this first part, though we do not see 

 how to give a better account of it in few words. So, again, the 

 second part might be said to contain an exposition of the doctrines 

 of permutations and combinations, and of probabilities, which is 

 closely connected with them, designed to lead up to the position 

 that " we cannot adequately understand the difficulties which beset 

 us in certain branches of science, unless we gain a clear idea of the 

 vast number of combinations or permutations which may be possi- 

 ble under certain conditions. Thus only can we learn how hope- 

 less it would be to attempt to treat nature in detail, and exhaust 

 the whole number of events that might arise" (vol. i. p. 216). Yet 

 this is not an adequate statement of the aim of Book II. ; and the 

 same would be found true of similar statements made in regard to 

 the other books. Of course, in the case of any elaborate treatise 

 the same may to some extent be true ; but in the work before us 

 the difficulty assumes unusually large dimensions, and renders the 

 task of the reviewer peculiarly hard. 



Probably the merit of the work lies mainly in the acute remarks 

 which are freely scattered through it, and in discussions of parti- 

 cular points, which are often of great interest, and for the sake of 

 which alone the work is well worth perusal. As an instance of 

 this we will give a brief account of a single chapter (the twenty- 

 sixth), which concludes the fourth book on " Inductive Investiga- 

 tion ;" it is headed, " Character of the Experimentalist." After 

 insisting on the impossibility that the efforts of many ordinary 

 men should supply the place of the genius of exceptional men, and 

 remarking that " nothing is less amenable than genius to scientific 

 analysis and explanation," our author goes on to specify some of 

 the mental characteristics of the natural philosopher. His mind 

 must be readily affected by the slightest exceptional phenomena ; 

 his associating and identifying powers must be great ; his imagina- 

 tion active ; his powers of deductive reasoning sure and vigorous ; 

 and he must have so strong a love of certainty as to lead him to 

 compare with diligence and candour his speculations with fact and 

 experiment. It is sometimes thought that the philosopher will be 

 cautious in following up trains of speculation ; and the notion 

 derives some countenance from the fact, that only successful trains 

 of thought are commonly reserved for publication. But Mr. Jevons 

 points out, from the examples of Kepler and Faraday, that, to use 

 the words of the latter, " in the most successful instances not a 

 tenth of the suggestions, the hopes, the wishes, the preliminary 

 conclusions have been realized." He then considers the method 

 pursued by Newton in the ' Principia' and the ' Optics' as a type of 

 the true scientific method "of deductive reasoning and experi- 

 mental verification." The chapter ends with a notice of a charac- 

 teristic of the philosophic mind, to which we have never before had 

 our attention so pointedly drawn, and which is well illustrated by 



