CH. xiil. WRITINGS OF DESCARTES. 103 



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 six- 

 teenth century had thought it a sufficient answer to Vesalius 

 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 

 Copernican theory when they made Galileo recant. Autho- 

 rity 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 we have never tried, but we think it probable 

 Aristotle was right until some one shows us that he was mis- 

 taken ;' if they had gone to the Tower of Pisa in this spirit, 



