418 PROCEEDINGS OF THE AMERICAN ACADEMY 



A like degree of historical error is commonly committed in reference to 

 another point which will come to be treated of in this paper, allied, at 

 least, as it is most intimately, with the subject of comprehension and ex- 

 tension, inasmuch as it also is founded on a conception of a term as a 

 whole composed of parts, — I mean the distinction of clear and distinct. 

 Hamilton tells us " we owe the discrimination to the acuteness o^ 

 the great Leibniz. By the Cartesians the distinction had not been 

 taken ; though the authors of the Port Royal Logic came so near that 

 we may well marvel how they failed explicitly to enounce it." (Lec- 

 tures on Logic ; Lecture IX.) Now, in fact, all that the Port Royal- 

 ists say about this matter * is copied from Descartes,t and their 

 variations from his wording serve only to confuse what in him is 

 tolerably distinct. As for Leibniz, he himself expressly avows that 

 the distinction drawn by Descartes is the same as his own. $ Never- 

 theless, it is very much more clear with Leibniz than with Descartes. 

 A philosophical distinction emerges gradually into consciousness ; there 

 is no moment in history before \vhi('h it is altogether unrecognized, and 

 after which it is perfectly luminous. Before Descartes, the distinction 

 of confused and distinct had been thoroughly developed, but the difier- 

 ence between distinctness and clearness is uniformly overlooked. 

 Scotus distinguishes between conceiving confusedly and conceiving the 

 confused, and since any obscure concept necessarily includes more 

 than its proper object, there is always in what is obscurely conceived 

 a conception of something confused ; but the schoolmen came no nearer 

 than this to the distinction of Descartes and Leibniz. 



§ 2. Of the Different Terms applied to the Quantities of Extension and 



Comprehension. 



Extension and comprehension are the terms employed by the Port 

 Royalists. Owing to the influence of Hamilton, intension is now fre- 

 quently used for comprehension ; but it is liable to be confounded with 

 intensity, and therefore is an objectionable word. It is derived from 

 the use of cognate words by Cajetan and other early writers. Exter- 

 nal undi internal quantity are the terms used by many early Kantians. 



If we were to go to later authors, the examples would be endless. See any com- 

 mentary in Phys. Lib. I. 



* Part I. chap. ix. t Principia, Part I. § 45 e/ seq. 



\ Eighth Letter to Burnet. 



