SECT. XIV. 2. 2. OF IDEAS. 83 



number, and of the mathematical fciences, which are concerned 

 in the menfurations or proportions of figure. 



This I imagine may have in part arifen from the prepoflef- 

 fion, which has almoft univefally prevailed, that ideas are im- 

 material beings, and therefore poffefs no properties in common 

 with folid matter. Which I fuppo'ed to be a fanciful hypothefis 

 like the ftories of ghofts and apparitions, which have fo long 

 amufed, and dill amufe the credulous without any foundation 

 in nature. 



The exiftence of our own bodies, and of their folidity, and of 

 their figure, and of their morions, is taken for granted in my 

 account of ideas ; becaufe the ideas themfelves are believed to 

 confift of motions or configurations of folid fibres ; and the 

 queftion now propofed is, how we become acquainted with the 

 figures of bodies external to our organs of fenfe ? Which I can 

 only repeat from what is mentioned in Set. XIV. 2. 2. t'iat 

 if part of an orgnn of fenfe be (lirnulated into aftion, as of the 

 fenfe of touch, that part fo ftimuhted into aclion muft pofTefs 

 figure, which mufl be fimilar to the figure of the body, which 

 ftirnulates it. 



Another previous prepofleflion of the mind, which may have 

 rendered the manner of our acquiring the knowledge of figure 

 lefs intelligible, may have arifen from the common opinion of 

 the perceiving faculty refiding in the head ; whereas our daily 

 experience Chews, that our perception (which confilts of an idea, 

 and of the pleafure or pain itoccafions) exifts principally in the 

 organ of fenfe, which is Simulated into aftion ; as every one, 

 who burns his finger in the candle, mufl be bold to deny. 



When an ivory triangle is prefTed on the palm of the hand, 

 the figure of the furface of the part of the organ of touch thus 

 compreffed is a triangle, refembling in figure the figure of the 

 external body, which comprefTes it. The a&ion of the (Iimu- 

 lated fibres, which conflitute the idea of hardnefs and of figure, 

 remains in this part of the fenforium, which forms the fenfe of 

 touch ; but the fenforial motion, which confbtutes pleafure or 

 pain, and which is excited in confequence of thefe fibrous mo- 

 tions of the organ of fenfe, is propagated to the central parts of 

 the fenforium, or to the whole of it ; though this generally oc- 

 curs in lets degree of energy, than exift> in the ftimulated or- 

 gan of fenfe ; as in the inftance above mentioned of burning a 

 finger in the candle. 



Some, who have efpcufed the doclrine of the immateriality of 

 ideas, have ferioufly doubted the exiftence of a material world, 

 with which only our fenfes acquaint us j and yet have affented 

 to the exiftence of fpirit, with which our fenfes cannot acquaint 



us; 



