Chap. I. APPENDIX. 311 



that were really the cafe, I fhould be very clear for giving up all 

 Sir Ifaac's fine demonftratlons, rather than fupport them upon prin-' 

 ciples which, I think, fhake the very foundation ofTheifm. If 

 we fliould do fo, it would be no more than leaving afbronomy as ic 

 was before Sir Ifaac wrote, that is, a mere colleclion of faiSts and 

 obfervations, without fyftem or fcience*. But, I think, I have {l\o\Vn 

 that all Sir Ifaac's demonftrations will ftand firm upon a folid bottom, 

 if we only make a mod obvious and eafy analyfis of the Planetary 

 Motion, by confidering feparately the defcent of the planet from the 

 tangent, and its progreffive Motion in its orbit. It is true, that this de- 

 fcent cannot exift without the progreffive Motion. But neither can 

 the dimenfions of Body exift v.-ithout Body, nor furfaccs Vvithout 

 folids ; yet Euclid has confidered them feparately ; and upon that 

 abftradion all his demonftrations arc founded, though it be an ab- 

 ftradion merely ideal, Vx^hich can only be made by the Intellc<Sl, Hut 

 cannot be perceived, by the Senfe, nor figured even by the Imagina- 

 tion. Nor in geometry only are fuch abftradions common, but in 

 all other fciences. Thus, in logic, we confider the Attribute fepa- 

 rately from the Subjed: ; though, neither in fait, nor even in ima- 

 gination, can the Attribute exift without the Subjed. In metaphy- 

 fics, we confider Motion by itfelf, abftra£ted from any body mo- 

 ved, and yet fuch abftradlion is by nature impoffible to exift : And, 

 in like manner, w^e confider Matter as diftind from Body, that is, 

 without extenfion, or any other of the qualities we afcribe to Body ; 

 and yet fuch matter no where exifts, as far as we know. In morals, 

 we confider Appetites, Inclinations, Opinions, and Will, without ta- 

 king into our confideration the fubjcd: of thefe, though, without 

 fuch fubjed, it is impoftible they can exift. And, in general, I will 

 venture to affirm, that no fcience can be taught or learned, without 

 abftrading, and confidering feparately, things that cannot exift but 



in conjunction *'. 



But, 



* Vol. ii. p. 410. 421. 



f See more of this, Vol. ii. p. 422 



