ISO ANTIENT METAPHYSICS. BookIL 



that the fliadovvs of them are projeded upon the bottom of the cave, 

 and which, therefore, the prifoners fee, though they cannot fee the 

 fubftances *. This may be thought to be one of Plato's vifionary 

 notions, which amufes the fancy, without informing the underftand- 

 ing ; and, indeed, it is sparable, (a manner of teaching in which an- 

 tient wifdom delighted much,) but a parable mofl: expreflive of truth 

 and reality ; and the interpretation of the parable I take to be this : 



Our ideas, by which only we know any thing, are all poflerior to 

 our fenfations ; our knowledge, therefore, we have only at fecond 

 hand, refleded, as it were, from material things : Whereas higher in- 

 telligences are converfant, we muft fuppofe, with the original ideal 

 forms, not fecondary, or derived from matter, like thofe which are the 

 objeds of our knowledge. Thus, therefore, like Plato's prifoners, wc. 

 fee not the things themfelves, but certain reprefentations or fnnilitudee 

 of them, w^hich may very properly be compared to Ihadows. 



Further, the notions we get in this way, mufl: appear exceedingly 

 iraperfe(St, if we confider that fenfation is nothing elfe but the commu- 

 nication of motion from the external objed; to the mind or fentient 

 part, through the medium of what is called the organs of Jhi/g ; for 

 that all objeds of fenfe are perceived by fome impreffion which they 

 make upon thefe organs, is a thing well known to all philofophers : 

 And the only difference among our fenfations is, that the motion from 

 fome of thefe objed:s is communicated to the organ at a greater di- 

 flance, and fome at a lefs, or in contact. 



1 will take, for example, the fenfe of feeing, which Is our mofl ex- 

 cellent fenfe, and that to which, according to Arillotle's obfervation f, 

 we owe the greateft part of our knowledge. 1 ufe it as an example 

 for another reafon alfo ; becaufe the way in which vilible objedts ope- 

 rate 



• Plato De Kfpvb. lib. 7 in initio. 

 f Metaph. lib. 1. in initio. 



