ULTIMATE SCIENTIFIC IDEAS. 55 



Matter could not, as Leibnitz suggested, be composed of un- 

 extended monads (since the juxta-position of an infinity of 

 points having no extension, could not produce that exten- 

 sion which matter possesses) ; and perceiving objections to 

 the view entertained by Newton; Boscovich proposed an in- 

 termediate theory, uniting, as he considered, the advantages 

 of both and avoiding their difficulties. His theory is, that 

 the constituents of Matter are centres of force — points with- 

 out dimensions, which attract and repel each other in such- 

 wise as to be kept at specific distances apart. And he 

 argues, mathematically, that the forces possessed by such 

 centres might so vary with the distances, that under given 

 conditions the centres would Temain in stable equilibrium 

 with definite interspaces; and yet, under other conditions, 

 would maintain larger or smaller interspaces. This specu- 

 lation however, ingeniously as it is elaborated, and eluding 

 though it does various difficulties, posits a proposition which 

 cannot by any effort be represented in thought: it escapes 

 all the inconceivabilities above indicated, by merging them 

 in the one inconceivability with which it sets out. A centre 

 of force absolutely without extension is unthinkable: an- 

 swering to these words we can form nothing more than a 

 symbolic conception of the illegitimate order. The idea of 

 resistance cannot be separated in thought from the idea of 

 an extended body which offers resistance. To suppose that 

 central forces can reside in points not infinitesimally small 

 but occupying no space whatever — points having position 

 only, with nothing to mark their position — points in no re- 

 spect distinguishable from the surrounding points that, are 

 not centres of force; — to suppose this, is utterly beyond 

 human power. 



Here it may possibly be said, that though all hypotheses 

 respecting the constitution of Matter commit us to incon- 

 ceivable conclusions when logically developed, yet we have 

 reason to think that one of them corresponds with the fact. 

 Though the conception of Matter as consisting of dense in- 



