OK THE ESSENTIAL PROPERTIES OF MATTER. 6l5 



pulsion, or all repulsion to a modification of attraction, we should make an 

 improvement of the same kind, as Newton made, when he reduced all the 

 diversified motions of the heavenly bodies to the universal laws of gravitat ion. 

 only. We have, however, at present, little prospect of such a simplifij 

 tion. 



It has been of late very customary to consider all the phenomena of nature lp^^,, '' 

 as derived from the motions of the co rpuscles of matter, agitated by forces 

 varying according to certain intricate laws, which are supposed to be pri- 

 mary qualities, and for which it is a kind of sacrilege to attempt to assign 

 any ulterior cause. This theory was chiefly introduced by Boscovich, and it has 

 prevailed very widely among algebraical philcsoj.hers, who have been in the 

 habit of deducing all their quantities from each other by mathematical rela- 

 tions, making, for example, the force a certain function or power of the dis. 

 tance, and then imagining that its origin is sufficiently explained; and when 

 a geometrician has translated this language into his own, and converted th^ 

 formula into a curve, with as many flexures and reflections as the labyrinth 

 of Daedalus, he imagines that he has depicted to the senses the whole pro- 

 cedure of nature. Such methods may often be of temporary advantage, as long 

 as we are contented to consider them as approximations, or as classifica- 

 tions of phenomena only; but the grand scheme of the universe must surely* 

 amidst all the stupendous diversity of parts, preserve a more dignified sim- 

 plicity of plan and of principles, than is compatible with these complicated 

 Suppositious. 



" To show", says Newton, in the preface to the second edition of 

 his Optics, " that 1 do not take gravity for an essential property" of 

 bodies, I have added one question concerning its cause, choosing to 

 propose it by way of a question, because I am not yet satisfied about 

 it, for want of experiments." In the query here mentioned, he pro- 

 ceeds from the supposition of an elastic medium, pervading all space ; 

 a supposition, which he advances with considerable confidence, and which 

 he supports by very strong arguments, deduced as well from the phe- 

 nomena of light and heat, as from the analogy of the electrical and mag- 

 netic influences. This medium he supposes to be much rarer within the 

 dense bodies of the sun, the stars, the planets, and the comets, than in. 



