xlvlii PREFACE. 



to me to have a greater affinity than any other with Ariftotle*s 

 Logic, as both muft neceflarily difled: and examine carefully the ope- 

 rations of the human mind ; and accordingly Ariftotle, in one of his 

 logical works, viz, his book of Literpretation^ has confidered accu- 

 rately fome of the parts of fpeech into which grammar has divided 

 language, fuch as the Verb and the Noun. Now, though the Art 

 of Language be, no doubt, a moft wonderful Art, and perhaps the 

 greateft invention of men, if it be confidered tliat it muft have been 

 anion-;*- the firft, I hold Ariftotle's Logical Art to have been ftill a 

 greater difcovery, though coming, no doubt, much later, and, I 

 believe, after every other Art was invented; for it analyfes 

 what I think is ftill more various and complicated than Speech, 

 I mean Rcafonhig^ in all the various forms and figures in which it 

 appears. 



It is evident that all reafoning muft confift of propofttions put 

 t0G;ether in a certain way ; and thefe propofitions again muft confift 

 gf fimple terms, joined together in a certain way. The analyfis, 

 therefore, of Reafoning muft of neceffity be fuch as Ariftotle has 

 made, ftrft, into fimple terms ; fecondly, into propofitions ; and, 

 thirdly, into fyllogifm, which, as the name imports, is a coUedion 

 of propofitions from which the conclufion is inferred ; and there the 

 procefs of Reafoning ends. 



With refped to fmplc terms^ it is evident that if they could not 

 have been reduced to certain clafles, there could have been no 

 Science of Reafoning ; and it was ncceflary alfo that thefe clafles 

 fhould be reduced to a certain number, for in Science there is no- 

 thing infinite. Now this great and fundamental work of Logic is 

 performed in the book of Categories, and without this difcovery 

 there could not have been, as I have fhewed elfewhere*, a definition 



of 



* Vol. I. Origin of Language, p. 74, ct feq. 2d edit. 



