30 OF REPRODUCTION 



ciples, to iifages, to inftruments, &c. All thefe 

 adminicles are efforts of human genius, and be- 

 long more or lefs to the abftradion of our ideaSr 

 This abltradion, with regard to us, conftitutes 

 the fimplicity of things ; and tlie difficulty of re- 

 ducing them to this abliraOion is the compound, 

 Extenfion, for example, being a general and ab- 

 ftradt property of matter, is not iriueh com- 

 pounded. In order, however, to judge concern- 

 ing it, we have imagined fome extenfions to 

 have no thicknefs, others to have neither thick- 

 nefs nor breadth, and points, which are exten- 

 fions without being extended. All thefe abftrac- 

 tions have been invented as fupports to the un- 

 derftanding ; and the few deiiniiions employed 

 in geometry have given rife to numberlels pre- 

 judices and falfe conceptions. Whatever is re- 

 ducible under any of thefe defmitions is called 

 fimple ; and fuch things as cannot be eafily re- 

 duced to this ftandard are confidered as complex. 

 Thus, a triangle, a fquare, a circle, a cube, and 

 alfo thofe curves of which we know the geome- 

 trical properties, are regarded as fimple. But 

 every thing which we cannot reduce under thefe 

 figures, or abftrad: rules, appears to us to be com- 

 ' plex. We never refledl, that all thefe geometri- 

 cal figures exift no where but in our own imagi- 

 nations, or that, if they are ever found in Na- 

 ture, it is only becaufe fhe exhibits every pof- 

 fible form ; and the appearance of fimple figures^ 

 as an exadl: cube, or an equilateral pyramid, is, 



perhaps. 



