426 ANTIENT METAPHYSICS. BookV. 



monflrated. The application to this cafe is obvious ; for there, as in 

 the cafe of the Planets, we difcover the Moving Force by the Hy- 

 pothefis of the Body being moved by a Force ading in two Straight 

 Lines : And the only difference I can obferve betwixt the two cafes 

 is, that the Hypothefis, in the cafe of the Planets, appears to be 

 more obvious, and arifmg more naturally from the Planetarj'- Mo- 

 tion, than the other Hypothefis arifes from the Motion in the 

 Straight Line. 



Some Newtonians will fay, that their conclufions, deduced not from 

 Hypothefes, but from Realities, are more convincing. But my anfwer 

 is, that, if the Hypothefes are admitted, the Dedudions from them 

 are as certain as if they were Realities, as in the two inftances I have 

 given ; fo that the only queftion is. Whether they be Hypothefes 

 abfurd or impoffible, and, therefore, fuch as cannot be admitted ? 

 Now, the Newtonians, who maintain that they are Realities, will 

 certainly not fay fo. Nor will any one be difpofed to think fo, when 

 he confiders, that with thefe Hypothefes all the phaenomena of the 

 Planetary Motion perfedly agree ; and that from them, among other 

 phaenomena, the wonderful proportion, which Kepler difcovered, be- 

 twixt the Periods of the Revolutions and the Dillances from the Centre, 

 can be deduced. But this, notwithftanding, if it could be fliewn that 

 the Planetary Motion could not be produced in the way fuppofed, 

 I fhould fay, that though the Conclufions, being agreeable to the 

 Phaenomena were true, the Principles from which they were de- 

 duced were not true, and confequently that the Reafoning, proceed- 

 ing upon falfe Principles, was not juft ; and I fhould fay the fame 

 of the hypothetical Reafoning, with refped to the Compoiition of 

 Motion, if it could be proved, that it was impoffible the Motion 

 could be produced by the Adion of two Bodies in the way fuppofed. 

 But this cannot be faid, and certainly no Newtonian will fay, that 

 . the Hypothefis is impoffible of the Planetary Motion being pro- 

 duced, as I fuppofe, when he avers that it is aHuaUy fo produced. 



I will 



