358 FALLACIES. 



the proposition that what is inconceivable cannot be 

 true were suffered to remain unquestioned as a specu- 

 lative truth, it would be a truth upon which no prac- 

 tical consequence could ever be founded, since, upon 

 this showing, it is impossible to affirm of any proposi- 

 tion, not being a contradiction in terms, that it is 

 inconceivable. Antipodes were really, not fictitiously, 

 inconceivable to our ancestors: they are indeed con- 

 ceivable to us; and as the limits of our power of 

 conception have been so largely extended, by the 

 extension of our experience and the more varied exer- 

 cise of our imagination, so may posterity find many 

 combinations perfectly conceivable to them which are 

 inconceivable to us. But, as beings of limited expe- 

 rience, we must always and necessarily have limited 

 conceptive powers; while it does not by any means 

 follow that the same limitation obtains in the possi- 

 bilities of nature, nor even in her actual manifesta- 

 tions. 



Rather more than a century and a half ago it was 

 a philosophical maxim, disputed by no one, and which 

 no one deemed to require any proof, that " a thing 

 cannot act where it is not." With this weapon the 

 Cartesians waged a formidable war against the theory 

 of gravitation, which, according to them, involving 

 so obvious an absurdity, must be rejected in limine: 

 the sun could not possibly act upon the earth, not 

 being there. It was not surprising that the adherents 

 of the old systems of astronomy should urge this 

 objection against the new; but the false assumption 

 imposed equally upon Newton himself, who in order 

 to turn the edge of the objection, imagined a subtle 

 ether which filled up the space between the sun and 

 the earth, and by its intermediate agency was the 

 proximate cause of the phenomena of gravitation. 



