78 HISTORY of the SOCIETr. 



planation of natural appearances. But it involves, in the whole 

 of it, this great difficulty, that mathematical points are not only 

 capable of motion, but capable of being endowed, or, at lead, 

 diftinguimed, by phyfical qualities. Dr Hutton, in his theo- 

 ry, has avoided this difficulty, by giving no other than a nega- 

 tive definition of the matter which he fuppofes the elementa- 

 ry principle of body. On this account, though to the imagina- 

 tion his theory may want the charms which the other pofTefTes, 

 yet it has the advantage of going juft to the extent to which our 

 perceptions or our obfervations authorife us to proceed, and of 

 being accurately circumfcribed by the limits pointed out by the 

 laws of philofophical induction*. 



The exiftence of matter neither heavy nor inert, which he 

 had taken fo much pains to eftablifh, was applied by him to ex- 

 plain 



* Though Boscovich's Theory was publifhed long before Dr Hutton's, fo 

 early, indeed, as the year 1758, there is no reafon to think that the latter was in 

 any degree fuggefted by the former. Boscovich's theory was hardly known in 

 this country till about the year 1770, and the firft fketches of Dr Hutton's theory 

 are of a much older date. Befides, the method of reafoning purfued by the authors 

 is quite different ; and their conclufions, though alike in fome things, directly 

 contrary in others, as in what regards gravity, inertia, &.c. The Monads of Leib- 

 nitz might more reafonably be fuppofed to have pointed out to Dr Hutton the 

 neceffity of fuppofing the elements of body to be unextended, if the originality of 

 his own conceptions, and the little regard he paid to authority in matters of theo- 

 ry, did not relieve us from the neceffity of looking to others for the fources of his 

 opinions. 



The principal defect of his theory feems to me to confift in this, that it does not 

 flate with precision the difference between the conftitution of thofe powers which 

 fimply form matter, and thofe that form the more complex fubftance, body. In 

 other words, it does not explain what muft be added to matter to make it body. 

 The anfwer feems to me to be, that the addition of a repelling power, in all direc- 

 tions, is fufficient for that purpofe. Such a repulfion, if ftrong enough, would 

 produce both impenetrability and inertia. The matter, again, that poffefied only 

 an attractive power, like gravity, or a repulfive power only in a certain direc- 

 tion, like light, would not be inert nor impenetrable. In this inference, however, 

 from his fyflem, I am not fure if I fhould meet with the author's approbation. 



