234 HABIT AND INTELLIGENCK. [ch. xlv. 



tion, we are satisfied of the truth of the result, and do not 

 need to test it by counting or measuring. But I think, 

 though I do not wish to speak dogmatically on a question 

 which rather belongs to metaphysics than to logic, that the 

 reason why we do not demand verification for the results 

 of mathematical reasoning is only that general experience 

 assures us of their trustworthiness. But — to put a case 

 which, though not possible, is quite conceivable — if the 

 whole algebraic calculus had been invented before any part 

 of it was applied to actual use, I do not think that a 

 reasonable man would have been justified in feeling abso- 

 lutely certain of the truth of its results untH they had 

 been tested, checked, and verified. But this is not because 

 of anything uncertain or contingent in the nature of mathe- 

 matical truth ; it is only because of the limitation of our 

 powers. This remark, however, applies to all the sciences 

 alike ; it is only the limitation of human powers that 

 makes it necessary to verify the results of theoretic de- 

 duction by observation. We can imagine an intelligence 

 similar in kind to ours, though very much more powerful, 

 which should be able to calculate and predict all' the 

 special facts of nature by pure deduction from the primary 

 laws of matter and of life, and this with such unerring 

 certainty as to be independent of any verification by the 

 observation of facts. 

 Conclu- I have in several places insisted on the truth, that the 



universal tendency of science is to establish unity of laws 

 throughout nature ; and I believe that in the present work 

 I have done something to extend the domain of sound 

 scientific ideas, by showing that Habit and Intelligence are 

 both of them co-extensive with Life, with Mind, and with 

 History. But it is obvious that there must be somewhere 

 a limit to such generalizations as these : it is obvious 

 that all the facts of nature can never be brought under 

 a single law. It can never, for instance, be possible to 

 refer the laws of chemical combinations to those of motion 

 and gravitation ; and, as I have argued at some length, 

 it is equally impossible to dedixce Intelligence from Habit, 

 or from any unintelligent principle whatever. 



sion 



