SKETCH OF RENE DESCARTES. 837 



first nine months of his residence. He wrote from Amsterdam 

 to Balzac, who had expostulated with him for having withdrawn 

 himself from the world : " In this great city where I am, there 

 being no one except myself who is not in trade, every one is so 

 intent on his specnlations that I might stay here all my life 

 without being seen by any one. I walk out every day amid the 

 confusion of a great people with as much freedom and peace as 

 you could have in your garden walks, and I pay no more attention 

 to the men who pass before my eyes than you would to the trees 

 in your woods and the animals feeding there. Even the noise 

 they make works no more interruption to my thoughts than would 

 the rumbling of a brook." He resumed his studies in dioptrics. 

 Observations on parhelia gave the origin to his treatise on 

 Meteors. He entered with great ardor upon the study of medi- 

 cine and anatomy, and visited the butchers' shops every day to 

 witness the slaughter of animals, of which he brought parts 

 home to his rooms to be dissected at his leisure. His corre- 

 spondence with Pere Mersenne abounded in mathematical prob- 

 lems which the two exchanged with each other. He studied 

 astronomy and composed his Traite' du Monde, in which he avowed 

 the doctrine of the motion of the earth. On learning, however, 

 of the condemnation of Galileo, he suppressed this book, saying, 

 in a letter to Pere Mersenne : " All the things I have explained, al- 

 though I believe them to be supported by very certain and very 

 evident demonstrations, I would not for the world maintain 

 against the authority of the Church. . . . My desire to live in quiet 

 and continue the retired life I have begun makes me more con- 

 tent to see myself delivered from the fear of having gained more 

 fame than I wished for by my writing, than sorry for having 

 lost the time and trouble that I have taken in composing it." 



Descartes made three visits to France during his residence in 

 Holland. The first was in 1644, to settle family affairs after the 

 death of his father in 1640 ; the second was signalized by an award 

 to him of a pension secured by Cardinal Mazarin of three thou- 

 sand francs, in consideration of the advantages which his investi- 

 gations had conferred upon mankind, and to aid him in continu- 

 ing them ; the third visit ended in disappointment, for the sub- 

 stantial results anticipated from it were nullified by the breaking 

 out of the civil war of the Fronde. During the second of these 

 visits he is said to have met Pascal, and suggested to him the 

 thought of experimenting on the weight of the air. A visit was 

 made to England for the investigation of magnetic phenomena, 

 and in 1634 Descartes took an excursion into Denmark. 



A controversy in 1638 with Fermat concerning that author's 

 book on Maxima and Minima, and on tangents, engaged the 

 friends of both parties, and resulted in a friendship between the 



