342 ANTIENT METAPHYSICS. Book IIL 



But things are fo connecfted in this univerfe, and the one and the 

 many Co mixed together in every part of it, that things are not only 

 different, each from the other, but they alfo hold to one another by 

 fome common band or tie, fo that the one is to be found in them as 



well as the many ; and they are both the Jame and different. This 



is the cafe of number and magnitude^ as well as of other things ; for 

 they are not only different in the refpeds above mentioned, but they 

 are the fame in this refpeiSt, that they have both parts which may be 

 meafured or numbered : And it is for this reafon that, as Ariflotle has 

 obferved *, the terms equal or unequal^ can only properly be applied 

 to them. Whereas, of other things, we lay, that they are like or 

 unlike. They muft therefore belong to the fam.e genus ; and that 

 genus is what is called by the metaphyficians quantity^ and is divided 

 by them into continuous and difcrete, that is, magnitude and num- 

 ber t- 



As to motion, the mathematician takes It up according to common 

 •apprehenfion, and applies to it the principles of geometry and arith- 

 metic, without troubling himfelf to inquire concerning its nature, and 

 what rank it holds in the order of beings ; whereas, the metaphyficiaii 

 inquires into its nature and effence ; fhows that it has nothing fixed 

 or determinate in its nature, but Is a progrefs from one (late to ano- 

 ther : That, therefore, it is that which produces all things that are in 

 generation ; but that, therefore, it is not of the number of things ac- 

 tually produced and conftltuted, and, by confequence, none of the ca- 

 tegories — that it is in the thing tnoved^ not in that which moves ; and9 

 confequently, that the thing which moves may itfelf not be moved — 

 and, laJlly^ihdX what moves muft, of neceffity, be different from what 

 ts moved ; and, therefore, that nothing can move itjelf. 



The 



* Arlftot. Categ. cap. 6. injine. 



t Euclid, in his definitions, has not mentioned quantity, though jt be the genus of 

 the two fubjefts of which he treats, magnitude and number, becaufe it is an univerfal, 

 and a metaphyfical idea •, and the reafon probably why he has not defined magnitude, 

 though he has fo often mentioned it, is, that he could not have done it without taking 

 notice of quantity. 



