22 DESCARTES. 



co very o^ subsequent ones. Nor in this perhaps 

 snail I appear too vain, if it be considered that, as 

 the truth on any particular point is one, whoever 

 apprehends the truth, knows all that on that point 

 can be known. The child, for example, who has 

 been instructed in the elements of Arithmetic, and 

 has made a particular addition, according to rule, 

 may be assured that he has found, with respect to 

 the sum of the numbers before him, all that in this 

 instance is within the reach of human genius. Now, 

 in conclusion, the Method which teaches adherence 

 to the true order, and an exact enumeration of all 

 the conditions of the thing sought, includes all that 

 gjyses certitude to the rules of Arithmetic. 

 \ But the chief ground of my satisfaction with this 

 Method, was the assurance I had of thereby exercis- 

 ^ ing my reason in all matters, if not with absolute 

 perfection, at least with the greatest attainable by 

 me: besides, I was conscious that by its use my 

 mind was becoming gradually habituated to clearer 

 and more distinct conceptions of its objects; and I 

 hoped, also, from not having restricted this Method 

 to any particular matter, to apply it to the diffi- 

 culties of the other Sciences, with not less success 

 than to those of Algebra. I should not, however, 

 on this account have ventured at once on the exam- 

 ination of all the difficulties of the Sciences which 

 presented themselves to me, for this would have 

 been contrary to the order prescribed in the 

 Method, but observing that the knowledge of such 

 is dependent on principles borrowed from Philos- 

 ophy, in which I found nothing certain, I thought it 



