CO. D I S S E R T A T I O H O N 



body. This law, therefore, concerning the continuance of motion, is 

 to be underilood only of motion of that kind ; for, as to motion pro- 

 duced immediately and diredly by Mind, it is evident that Sir Ifaac 

 does not here fpeak of it, and 1 doubt whether he had any idea of it. 

 This motion, we know by the moll certain of all knowledge, viz. con- 

 fcioufnefs, continues no longer than the movmg power continues to 

 a*fl ; for it is in this wa,y that our minds move ourbodies. V/hat, there- 

 fore, I have faid, concerning the motion ot the celeftial bodies, upon 

 the fuppolition that it is produced by the immediate agency of Mind, 

 will hold good, even allowing this law ot Sir Ifaac's to be, true. 



As this law, concerning the continuance of motion, is exprefled, 

 one iliould imagine that it related only to motion in a ftraight linCv 

 and not to motion in a circle; but we muft alfo remember that, ac- 

 cording to Sir Ifaac's philolophy, all motion, even the circular, begins 

 in a ftraight line ; and, therefore, if the motion in a ftraight be per- 

 petual, fo muft the circular ; and, accordingly Sir Ifaac, in his expla- 

 nation of this firft law of motion, tells us, that a wheel, whofe parts, 

 by cohering, perpetually retrad it from the redilineal motion, does 

 not ceale to roll, except in fo far as it is retarded by the air. His 

 words are, ' Trochusy cujus partes cohaerendo perpetuo retrahunt fefe a 

 ' motibus refiihneis, non Cdjfut rotari nift quatenus ab acre retardatur^ 

 And he adds, ' Majora autem flanetarum ei cometarum corpora mctus 

 ^ JuQS'i et pfogrejjivos et circuUircsy inj'patiis minus reftfientibus fa6los, 

 * confcrvant diutius.^ What he fays here concerning the motion of 

 the celeftial bodies, he exprefies much more ftrongly in his Scholium 

 Gcnerale, with which he concludes his Principia, and plainly tells us, 

 that the motion of thofe bodies is perpetual, according to the laws of 

 motion that he has laid down, that is, by the vis infita^ and the 

 imprejjed force of gravity : * Corpora orimia in ijiis fpatiis liberrime 



mo* 



