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 almofl univerfally prevailed, that ideas are im- 

 material beings, and therefore poflefs no properties in common 

 with folid matter. Which I fuppofe to be a fanciful hypothefis, 

 like the flories of ghofls and apparitions, which have fo long 

 amufed, and Hill amufe the credulous without any foundation 

 in nature. 



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

 their figure, and of their motions, 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 Seel. XIV. 2. 2. that 

 if part of an organ of fenfe be flimulated into action, as of the 

 fenfe of touch, that part fo flimulated into action mull poflefs 

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

 Simulates it. 



Another previous prepofTeflion 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 fhews, that our perception (which confifls of an idea, 

 and of the pleafure or pain it occafions) exifts principally in the 

 organ of fenfe, which is flimulated into action ; as every one, 

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



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

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

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

 external body, which comprefles it. The adlion of the flimu- 

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

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

 touch ; but the fenforial motion, which conftitutes 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 lefs degree of energy, than it exifls in the flimulated or- 

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

 linger in the candle. 



Some, who have efpoufed the doctrine of the immateriality of 

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

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

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



us ; 



