Chap.Vr. ANTIENT METAPHYSICS. 423 



Moreover, It Is to be confidered, that the appearances In the phaft" 

 tafia are, for the greater part, voluntary ; for we can, by an a6t of 

 our w/7/, call up any Image in the phantafia that we pleafe ; but, as 

 to the perceptions of fenfe, they do not depend upon our will. 



Thefe arguments are, I think, fufiicient to convince even fuch as 

 are not philofophers, of the exiftence of things without us. But, with 

 refpecSt to the philofopher, who knows the nature of fenfation, and 

 how It is produced, one fingle argument is demonftrative ; for, in the 

 perceptions of fenfe, every man is confcious that he is paflive, and that 

 he is moved or excited to fenfation by fomething. Now, wherever 

 there is a patient^ there muft of neceffity be an agent. And, where- 

 ever any thing is moved, there muft of neceflity, as I have elfewhere 

 demonftrated *, be fomething that moves. As, therefore, the organ of 

 fenfe is moved, and fometimes In the moft fenfible manner — and, as 

 nothing can move itfelf, there muft needs be fomething different from 

 the organ, and which Is the thing that moves It. The motion, we 

 are confcious, is produced by Impulfe upon the organ ; and as nothing 

 can impel body but what has folidity and refiftence ; therefore I con- 

 clude, that what ads upon the organ is body as well as the organ it- 

 felf f. 



Fuither, 



• Page 67. etfequetu 



t It is in this way that Ariftotle argues againfl certain philofophers before his time, 

 fuch asHeraclitus and Protagoras, who, as he fays, maintained, that we were not fure of 

 the exiftence of any thing except our fenfations ; and that, therefore, they were the 

 only ftandard of truth and falfehood. According to this dodrine, fays Ariftotle, {f 

 there were no animals, nothing would exift, becaufe there would be no fenfation, 

 which is an affcaion of an animal. Now, we may fuppofe that no animal cxifts, and 

 therefore no fenfation, the confequence of which would be, according to' the 

 notion of thofe philofophers, that no fenfible objea, that is, objeft perceived 

 by the fenfe, exifts. But it is impolTible to fuppofe, that the things which 

 produce the fenfation fhould not exift, even without the fenfation ; for the 

 fenfation does not produce itfelf; but there neceffarily muft be fomething be- 

 fides the fenfation, which, in the order of nature, is prior to the fenfation; 

 for what moves is, by_ nature, prior to what is moved. The words are remark- 

 able. 



