//w.v/ in Mathematics and other Sde?}ces. I97 . 



ponent parts: this belongs to analysis. However, these things 

 do not take place in every instance, for all analyses arc not 

 perfect ; often we do not perceive the composition which 

 we seek, but by comparing" the properties which it manifests 

 v.ith those formerlv known from synthesis, without l)eing 

 able entirely to decompose it. In like manner, all syntheses 

 do not completelv succeed, and we mav reasonably suspect 

 that they are often accompanied with decompositions which 

 alter their truth. The objections of Delue against the new 

 theory appear to me to arise from these circumstances; and 

 without admitting them, they ought, in my opinion, to ren- 

 der us verv circumspect about the consequences we may de- 

 duce from experiments, so long as we are not sufficiently 

 acquainted with the nature of the eflects of light, lieat, 

 electricity, and, in general, of substances which arc in- 

 coercilile. 



The same reasons which caused the synthetical mode of 

 proof to be adopted in all the sciences, v/hen the geometers 

 only proceeded by theorems and corollaries, induced the me- 

 taphysicians of the middle of the last century to call that 

 method analytical which they made use of to manifest their 

 discoveries. Mathematics at that epoch enjoyed all the con- 

 sideration which chemistry and physics have acquired since. 

 The mathematicians who succeeded Newton had perfected 

 those theories which lieonly hinted at, and resolved questions 

 which he was not able to effect by the assistance of analysis. 

 The metaphysicians uere willing in some manner to asso^ 

 ciatc their labours with those of the mathematicians, and to 

 attaeli the revolution they had made in the systeai of ideas 

 to that which Newton had made in the system of the world, 

 Eut without being imposed upon by words, let vis examine 

 whetlicr their method merits the name which they have uiven 

 it, at least when it is compared with mathematical ana- 

 lysis. 



The writings of Condillac will furnish us with examples 

 of this method. In his treatise upon sensati(nis, he com-^ 

 mcnccs by supposing his statue solely to possess the sense 

 of smell, all others being abstracted; and he examines into 

 the nature of the ideas possible to be acquired solely by this 

 sense. In passing to the second chapter of this work, I 

 perceive, in the first paragraph, adetinition; in tlie second 

 and third paragraphia true theorems, that is to say, proposi- 

 tions lirst enumerated, and afterwards proved by tracin"- 

 them up to idcniie ideas. liy reading forwards in the same 

 chapter, and the remainder of the work, we may perceive 

 that be advances in a manner analogous to that followed in 

 N 3 elements 



