13 



assuredly the generality of mankind will not feel to be so." 

 It is a fact which I do not at all contest, that the generality 

 of mankind will not feel the Axioms of Chemistry, or even of 

 Mechanics, to be necessary truths. But I had said, not that 

 the generality of mankind would feel this necessity, but (in 

 a passage just before quoted by the Reviewer) that the mind 

 under certain circumstances attains a point of view from which 

 it can pronounce mechanical (and other) fundamental truths 

 to be necessary in their nature, though disclosed to us by 

 experience and observation. 



Both the Edinburgh Reviewer and Mr Mansel appear 

 to hold a distinction between the fundamental truths of 

 Geometry, and those of the other subjects which I have 

 classed with them. The latter says, that perhaps metaphy- 

 sicians may hereafter establish the existence of other sub- 

 jective conditions of intuitions (or, as I should call them, 

 Fundamental Ideas,) besides Space and Time, but that in 

 asserting such to exist in the science of Mechanics, I cer- 

 tainly go too far : and he gives as an instance, an Essay 

 which I added to the Second Edition of the Philosophy, 

 containing "a Demonstration that all matter is heavy." I 

 certainly did not expect that the Principles asserted in that 

 Essay would be assented to as readily or as generally as the 

 Axioms of Geometry ; but I conceive that I bare there 

 proved that Chemical Science, using the balance as one of its 

 implements, cannot admit "imponderable bodies" among its 

 elements. This impossibility will, I think, not only be found 

 to exist in fact, but seen to exist necessarily, by chemists, in 

 proportion as they advance towards general propositions of 

 Chemical Science in which the so-called " imponderable fluids" 

 enter. But even if I be right in this opinion, to how few will 

 this necessity be made apparent, and how slowly will the 

 intuition spread ! I am as well aware as my critics, that the 

 necessity will probably never be apparent to ordinary thinkers. 



