162 A NTI EN T MET A PHYSICS. Book. 11. 



What has induced men to believe that the mind could not perceive? 

 the objeds of fenfe, without the organs of fenfe, is a miRaken notion, 

 that thefe organs are the caufe of our fenfations, by which, no doubt, 

 they mean the efficient caufe ; but I deny that they arc even the in- 

 flrumental caufe; and, if we would (peak with ilri^t propriety, we 

 ought not to fay that we perceive, by the means of our feiilVs, but 

 we ought only to lav, that they remove the impediment, which would 

 elfe hinder our perception. It is, as if a perfon who Rood betwixt me 

 and an objesSl that I wanted to fee, (hould move out of the way : That 

 would not be, in any i'eni'c, the cuu/,; of my feeing the objcd, though 

 it would be that without which 1 could not fee it *. Now, the body 

 is to be confidered in like manner as an impediment to the perception 

 of the mind, which we may figure to ourfelves as fhut up in the dark 

 room above mentioned, with five peep-holes or inlets of the light, by 

 the means of which it perceives certain images reflected upon the wall. 

 In this way, the impediment to our perceptions is fo far removed, and 

 a total ecliple of the mind, which would otherwife take place, prevent- 

 ed ; but no new faculty, or even means of[ perception, is given. 



Let me fiippofe a man confined in fuch a dark chamber from his in- 

 fancy, with no other ufe of light but what he receives through a hole 



in 



* This dr{Hn£lion betwixt a cau/e, properly fo called, and that without which a 

 caufe could not operate, is a dillin^tion of great importance in philofophy. It is 

 made by Plato in the Phaedo, p. 74. editio Feint, in thefe words : «aao ^iv t« eo-rt t» 



«(T»«y ro) cfr;, «A>,« S* Exfoo, ^veu ov r« enTtov ovk ecv ttot^ «i) xiritv. Such things are Called, 



in the language of Ariftotle, «-t;v«c»T««, or co-caufes^ becaufe, without them, the princi- 

 pal caufes could not operate. But, of thefe, a difi:in£lion is to be made ; for fome of 

 them are really caufes, fuch as the tools with which an artift works, and fuch as the 

 bones and (inews of the human body, of which Plato, in the paffage here quoted, is 

 fpeaking, as it is by thefe that the mind moves the body. Thefe are called injlru- 

 mental r:i\i{i:s; and they are no other than the immediate efficient caufes of the cfFe<^s 

 proi^uced. The other kind of thefe e-vienrix^ and it is that of which I am now fpe^ik- 

 ing, is not even an inftrvmental caufe, though it be that without which the efficient 

 caufe could not operate, as it removes the impediment to the operation of that caufe. 



