i88 ANTIENT METAPHYSICS. Book IL 



followers have given up this way of accounting; for thefe motions ; 

 and, indeed, Sir Ifaac only propofes it as a query or conjecture *; fo 

 that, according to this philofophy, as it is now generally received, 

 there is no caufe fo much as pretended to be affii^ned for eifher of 

 thefe movements. But, 2^/k, Suppofe that the exiftence of fuch a 

 fluid {hould be admitted, and its efficacy to move fuch ponderous bo- 

 dies, ftill the queftion recurs, How is this fluid itfelf moved ? and 

 there are but two ways of anfwering that queftion ; either by admit- 

 ting an immaterial caufe, or byfuppofing another fubtile fluid, which 

 is to move the firfl: fluid ; and fo on, in iJifinitum ; which, as I have 

 obferved, is not accounting for the motion, even by an hypothefis. 



I mud: own, f think there is fome truth in Dr Cudworth's obferva- 

 tionf, that the philofophers of this age are feized with a kind o^ pneuma- 

 topkobia and hylomania^ a defperate averfion to mind^ and a paflionate 

 love for matter ; for, how elfe can I account for their fuppofing, with- 

 out either proof or probability, the exiftence of a fluid, and a fluid too 

 of fo extraordinary a kind, as not to have that property which they 

 fay is common to all bodies, I mean gravitation, rather than employ, 

 for folving the phaenomenon, a power which we are fure exifts in na- 

 ture, and which they admit produces motion, at leafl of one kmd, I 

 mean the animal motion ? 



But, fuppofe we (hould admit the exiftence of this invifible fluid, 

 How can we conceive it to produce the effeds afcribed to it ? It is a 

 known law of motion, that, when body moves body, the force is in 

 proportion to the mafs and velocity of the moving body ; or, as the 

 mathematicians exprefs it, in a ratio compounded of its mafs and ve- 

 locity. Now, fetting afide the motion of the celeftial bodies of fuch 

 prodigious mafs, and which are moved with fuch wonderful velocity, 

 let us confider the common phaenonjenon of heavy bodies falling to 

 the earth. This phaenomenon is fo common, that it does not fo much 



as 



• Newton's Optics, fecond edition, injine. 

 t Intelle£lual Syflem 



