THE PATH OF EVOLUTION 



He continued his mathematical and metaphysical 

 speculations during his camp life for some years, 

 until finally the reverses that the army met with and 

 that he witnessed in Hungary caused him to" relin- 

 quish his military position. After this he traveled 

 for some time in France, Holland, Switzerland, the 

 Tyrol, Italy, Venice and Rome. He never met 

 Galileo, nor did he ever appreciate his great dis- 

 coveries, showing that, admirable as Descartes was 

 in Geometry, he was ignorant of the true principles 

 of that method of observation which alone could 

 advance the knowledge of Physics. In 1629 he 

 retired into Holland, believing that he would not be 

 free in France to pursue his meditations. There he 

 worked at Metaphysics, Anatomy, Chemistry and 

 Astronomy. He composed a "Traite du Monde" as 

 he conceived it, but, hearing of the imprisonment of 

 Galileo, he feared to publish it. Probably the dread 

 of persecution was the cause of his adopting Tycho 

 Brahe's system of Astronomy, according to which the 

 sun and the planets moved around the Earth." 



At this date he had published no extended mathe- 

 matical works. Yielding to the solicitations of his 

 friends, he now gave to the world his " Traite de la 

 Methode," in which his mathematical discoveries 

 constituted one chapter only. He placed far higher 

 value upon his metaphysical writings than upon his 



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