DISCOURSE ON METHOD. 3 1 



of assurance, and cast aside the loose earth and 

 sand, that I might reach the rock or the clay. In 

 this, as appears to me, I was successful enough ; for, 

 since I endeavoured to discover the falsehood or 

 incertitude of the propositions I examined, not by 

 feeble conjectures, but by clear and certain reason 

 ings, I met with nothing so doubtful as not to yield 

 some conclusion of adequate certainty, although this 

 were merely the inference, that the matter in ques 

 tion contained nothing certain. And, just as in 

 pulling down an old house, we usually reserve the 

 ruins to contribute towards the erection, so, in 

 destroying such of my opinions as I judged to be ill- 

 founded, I ma4e a variety of observations and ac 

 quired an amount of experience of which I availed 

 myself in the establishment of more certain. And 

 further, I continued to exercise myself in the Method 

 I have prescribed ; for, besides taking care in general 

 to conduct all my thoughts according to its rules, I 

 reserved some hours from time to time which I 

 expressly devoted to the employment of the Method, 

 in the solution of Mathematical difficulties, or even 

 in the solution likewise of some questions belonging 

 to other Sciences, but which, by my having 

 detached them from such principles of these Sci 

 ences as were of inadequate certainty, were rendered 

 almost Mathematical: the truth of this will be 

 manifest from the numerous examples contained in 

 this volume.* And thus, without in appearance 

 living otherwise than those who, with no other 



*The Discourse on Method was originally published along 

 with the Dioptrics, the Meteorics, and the Geometry. Tr. 



