INFLUENCE ON RECENT SCIENCE 79 



Disc ours de la Methode, in the Principia Naturae, and 

 in the many letters of Descartes an unusually com- 

 plete record of his principles, his method, and his con- 

 clusions. 



In character, training, and opportunities, few if any 

 philosophers have been better equipped for their task 

 than Descartes. As has been said of him, " he is a 

 type of that spirit of science to which erudition and all 

 the heritage of the past seem but elegant trifling." He 

 believed and acted on the opinion that no scientific 

 knowledge is attainable unless men doubt ; unless they 

 put aside authority and rely on their own experience. 



Descartes has in his Principia Naturae set forth 

 with specious simplicity the causes, laws, and the phe- 

 nomena of the universe as he finds them. Geometry 

 is to be the ruler or at least the vicegerent, and no 

 substance will be discussed except such as may be 

 divided, figured, and moved according to the laws 

 which geometers hold to govern quantity, nor will 

 any proposition be considered proved unless it has 

 been deduced with such evidence as would suffice for a 

 mathematical demonstration. With vexatious incon- 

 sistency, he then destroys the force of this admirable 

 introduction by carefully warning us not to consider 

 his premises true or his conclusions conformable to 

 fact, since his scheme is really an hypothesis or sup- 

 position as to what might be and not what is. This 

 caution is usually attributed to his fear lest he should 



