i66 ■ ANTIENT METAPHYSICS. Book IIL 



7Jx,)i ; by which the mind pafles from one idea to another, compares 

 them together, forms propofitions and fyllogifms, and makes what 

 is called fc'ience. This diftindlion, betwixt that operation of our 

 intelled, by which we form our ideas, and the difcurfus mentis^ by 

 which we compare them together, and reafon upon them, is not 

 made by any of our modern philofophers: And yet, without it, we 

 cannot know what man is, according to Ariftotle*s definition of 

 him ; which is that of an animal capable of intelleEl aud fcience^ in 

 Greek vqm koli i'Tna-rrjy.rig hxTiKov: Meaning by vovg^ that firft opera- 

 tion of the intelledl, by which it forms ideas j and by i-TCtarrifjt.riy that 

 operation of the intelled:, by which it compares its ideas, and forms 

 what we call fc'ience^ and which the Greeks very properly called 

 iitiirn^ri^ as the mind then ftands ftill as it were, having finifhed 

 the operations upon its ideas. To fhow us what is truth or fcience, 

 is the profelTed defign of Ariftotle's Logic ; and, therefore, it 

 fliould be confidered as preparatory to the ftudy of philofophy and 

 of all arts and fciences, the bufmefs of which is to Invefligate truth 

 and to demonftrate. 



We have but one book in Englifh upon the fubjed of Logic, Mr 

 Locke's eflay upon the Human Underftanding, in two volumes ; 

 where he has faid a great deal upon Ideas, but little or nothing 

 upon the difcurfus mentis^ by which ideas are compared together, 

 and of them propofitions and fyllogifms formed. He has, in the 

 courfe of his work, mentioned propofitions; but he does not appear 

 to me to have known what a propofition was ; for he no where 

 makes the diftindion betwixt the praedicate, or attribute of a pro- 

 pofition, and the fubjcd of it. Now, without making that diftinc- 

 tion, it is impofTible to know what a propofition is : For, in every 

 propofition, there muft be fomething affirmed or denied ; and that 

 makes the Praedicate of the propofition: And there muft alfo be 

 fomething of which the praedicate is affirmed or denied ; and that 



is 



