78 HISTORY of the SOCIETr. 



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

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

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

 diftinguiflied, 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 pofleffes, 

 yet it has the advantage of going juil 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 induftion*. 



The exiflence of matter neither heavy nor inert, which he 

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

 plain 



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

 xarly, 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 fii-fl; flcetches of Dr Button's theory 

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

 is quite diflFerent ; and their conclufions, though alike in fome things, direftly 

 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 precifion the difference between the conftitution of thofe powers which 

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

 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 flrong enough, would 

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

 an attraftive 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 Ibould meet with the author's approbation. 



