Chap. ir. ANTIENT METAPHYSICS. 85 



ever momentary that ftate may be. The change, therefore, from 

 one ftate to another, never can be perceived by Senfe. — It may be 

 faid, I know, that the Senfe perceives the thing in one place, and 

 then, fome time after, in another ; and that this makes the Idea of 

 Motion, But I deny that Time is a perception of the Senfe ; for 

 Time is a Perception of the interval betwixt the changes of any 

 thing meafured by Motion, or, as Ariftotlc has defined it, it is the 

 perception of what i^firji and lajl in Motion, or, as he has given it, 

 in two words, it is the Number of Motion *. Now, I fay it is im- 

 poffible that the Senfe can have any perception of an interval, — of 

 firjl and lajl in Motion, or in any thing elfe ; becaufe Number, as 

 I have faid. Order and Succelfion, is no object of Senfe, but of Intel- 

 ledl. 



This account I have given of the Ideas of particular things agrees 

 with Plato's defcription of an Idea, — that it is the perception of the 

 one in the many ; for we mufi; perceive the one principal thing in any 

 objcdt, upon which all its qualities and accidents depend, otherwife 

 we cannot be faid to have an Idea of it. But the intelledt perceives 

 a greater one^ and which, therefore, forms what is truly called a 

 General Idea. Of this kind are the Ideas of Genus and Species, the 

 firft of thefe denoting an Idea more general than the other, and to 

 which the other is fubordinate : And there is the Idea of Difference 

 likewife a general Idea, by which the feveral fpeciefes of the fame 

 genus are diftinguifhed from one another. In all thefe Ideas, the 

 Mind muft perceive one nature common to viany things, and which 

 is called, in the language of Greek philofophy, the to x«93Aou, oppo- 

 fed to the t* xaSsxao-ra, that is, the fame Nature perceived only in in- 

 dividuals. 



This 



