CH. xin. WRITINGS OF DESCARTES. 105 



Descartes' Condemnation of Ignorant Assertion. Rend 

 Descartes, by his philosophy, assisted science in another way. 

 He was a Frenchman, born in Touraine in 1596, and he 

 became one of the most famous philosophers of France. He 

 wrote a great deal on science, especially on mathematics and 

 geometry, and also on the nature of man ; but the point 

 which we have to notice here was his belief that to arrive at 

 the real truth was the only thing worth living for. 



You will remember how the men of science of the 

 sixteenth century had thought it a sufficient answer to Vesa- 

 lius or to Galileo to say that Galen or Aristotle had decided 

 questions of anatomy and physics ages ago ; and how the 

 judges of the Inquisition thought they had crushed the Co- 

 pernican theory when they made Galileo recant. Authority 

 was the idol to which these people bowed down, and they 

 considered it rank heresy to doubt anything which had been 

 taught by their forefathers. But Descartes said, ' It is not 

 true to say we know a thing simply because it has been told 

 us. It is a duty to obey authority, to submit to the laws and 

 religion of our country and parents, and in matters where 

 we are not able to judge, it is wise to receive what is told 

 us by those who know more than we do. But to know 

 anything requires more than this, and unless the reasons 

 for any belief are so clear to our minds that we cannot doubt 

 them, we have no right to say we know it to be true, but 

 only that we have been told so.' 



I think you can see how this rule of Descartes, that it is 

 often more honest to doubt than to be quite sure without 

 good grounds, would influence science. If scientific men in 

 the time of Galileo, instead of saying ' We know that a heavy 

 weight falls more quickly than a light one because Aristotle 

 said so,' had said more modestly, ' We do not know, because 



