Additional Notes. 43^ 



modern genius. It has been substantially adopted, by Mr. 

 MiTCHEL, of Great-Britain, by Dr. Priestley, and by 

 some other distinguislied writers on the physical sciences, who 

 all regard it as relieving philoso[)hy from many pressing dlf5- 

 culties, and opening the way to much new and important 

 light. One great objection to this system immediately pre- 

 sents itself to the mind, and has been forcibly urged against it, 

 viz. If every particle of matter be strictly incxtendcd, where- 

 in does it differ from that eiis rationis, a mathematical point, 

 without parts or magnitude ? or rather, wherein docs it differ 

 from a mere point of space? Will not the adoption of this 

 system conduct its advocate a step furdier, and lay him under 

 the necessity of denying the real existence oi:\. material world, 

 and of supposing that what we call by tliat name is a mere 

 system of attractions and repulsions, without any substance 

 in which they can inliere ? It is proper to observe, that Bos- 

 coviCH was aware of this objection, and answered it by de- 

 nying that extension is a necessary attribute of matter. But is 

 not this a petitio principii? And if it be admitted, we may 

 well ask, wherein does matter^ according to this philosopher, 

 differ from spirit? 



Leibnitz had taught before Boscovich that the iirsl: 

 principles of matter are inextcnded points. The principal 

 difference between the moimds of the former, and the inex^' 

 tended atoms of the latter, lies in the qualities or forces with 

 which tliey are represented as endowed. The attractive and 

 repulsive powers of Boscovich differ materially from the 

 active and perceptive powers of Leibnitz, which he con- 

 sidered as sufficient not only to actuate the monad at a parti- 

 cular point of time, but also to produce all the changes which 

 it undergoes from the beginning to eternity. 



Boscovich seems to have been tlie first of mankind who 

 rejected all immediate contact between bodies, and their con- 

 stituent particles. In this way he got rid of the difficulty of 

 supposing an extended substance to be made up of inextcnded 

 points. Leibnitz, by not resorting to the sy.me hold doc- 

 irine, left this difficulty lying in all its force against his system. 



Electricity, p. 25. 



My friend, Peter Wilson, LL. D. tlie learned and ev:- 

 cellcnt Piofessor of die Latin and Greek Languages in Colum- 

 bia College, has suggested to me that, in detailing tlie cxpe- 



