178 EEASONING. 



show, that our capacity or incapacity of conceiving a thing has very little 

 to do with the possibility of the thing in itself; but is in truth very much 

 an afPair of accident, and depends on the past history and habits of our 

 own minds. There is no more generally acknowledged fact in human na- 

 ture, than the extreme difficulty at first felt in conceiving any thing as pos- 

 sible, which is in contradiction to long established and familiar experience ; 

 or even to old familiar habits of thought. And this difficulty is a necessary 

 result of the fundamental laws of the human mind. When we have often 

 seen and thought of two things together, and have never in any one in- 

 stance either seen or thought of them sepai'ately, there is by the primary 

 law of association an increasing difficulty, which may in the end become 

 insuperable, of conceiving the two things apart. This is most of all con- 

 spicuous in uneducated persons, who are in general utterly unable to sepa- 

 rate any two ideas which have once become firmly associated in their 

 minds; and if persons of cultivated intellect have any advantage on the 

 point, it is only because, having seen and heard and read more, and being 

 more accustomed to exercise their imagination, they have experienced their 

 sensations and thoughts in more varied combinations, and have been pre- 

 vented from forming many of these inseparable associations. But this ad- 

 vantage has necessarily its limits. The most practiced intellect is not ex- 

 empt from the universal laws of our conceptive faculty. If daily habit 

 presents to any one for a long period two facts in combination, and if he is 

 not led during that period either by accident or by his voluntary mental 

 operations toHhink of them apart, he will probably in time become incapa- 

 ble of doing so even by the strongest effort; and the supposition that the 

 two facts can be separated in nature, will at last present itself to his mind 

 with all the characters of an inconceivable phenomenon.* Thei'e are re- 

 markable instances of this in the history of science : instances in which the 

 most instructed men rejected as impossible, because inconceivable, things 

 which their posterity, by earlier practice and longer perseverance in the at- 

 tempt, found it quite easy to conceive, and which every body now knows 

 to be true. There Avas a time when men of the most cultivated intellects, 

 and the most emancipated from the dominion of early prejudice, could not 

 credit the existence of antipodes ; were unable to conceive, in opposition 

 to old association, the force of gravity acting upward instead of downward. 

 The Cartesians long rejected the Newtonian doctrine of the gravitation of 

 all bodies toward one another, on the faith of a general proposition, the re- 

 verse of which seemed to them to be inconceivable — the proposition that a 

 body can not act where it is not. All the cumbrous machinery of imagi- 

 nary vortices, assumed without the smallest particle of evidence, appeared 

 to these philosophers a more rational mode of explaining the heavenly mo- 

 tions, than one which involved what seemed to them so great an absurdity.f 



* "If all mankind had spoken one language, we can not doubt that there would have been 

 a powerful, perhaps a universal, school of philosophers, who would have believed in the in- 

 herent connection between names and things, who would have taken the sound yuan to be the 

 mode of agitating the air which is essentially communicative of the ideas of reason, cookery, 

 bipedality, etc." — De Moi-gan, Formal Logic, p. 246. 



t It would be difficult to name a man more remarkable at once for the greatness and the 

 wide range of his mental accomplishments, than Leibnitz. Yet this eminent man gave as a 

 reason for rejecting Newton's scheme of the solar system, that God could not make a body re- 

 volve round a distant centre, unless either by some impelling mechanism, or by miracle: 

 "Tout ce qui n'est pas explicable," says he in a letter to the Abbe Conti, " par la nature des 

 creatures, est miraculeux. II ne suffit pas de dire : Dieu a fait une telle loi de nature ; done 

 la chose est naturelle. II faut que la loi soit executable par les natures des creatures. Si 



