838 THE POPULAR SCIENCE MONTHLY. 



chiefs. Descartes had other discussions — with Petit on dioptrics, 

 Morin on light, Beaugrand on geostatics, Roberval on the line 

 described by a nail on the outside of a wheel in motion, and with 

 Voet, Professor of Theology at Utrecht. The last controversy, 

 which was brought on by Voet's criticisms of the indiscreet utter- 

 ances of Descartes's disciple, Regius, resulted in Descartes being 

 summoned before the magistrates of Utrecht on charges of irre- 

 ligion and slander. He escaped the threatened prosecution by 

 claiming the protection of the French ambassador and the Prince 

 of Orange. An order forbidding all mention of the name of Car- 

 tesianism at the University of Leyden was likewise annulled by 

 direction of the Prince of Orange. 



Queen Christina of Sweden, interested in her way, although 

 she was not yet twenty years old, in matters of literature and 

 philosophy, having heard of the great fame of Descartes, conceived 

 a desire to become acquainted with him. He was drawn into a 

 correspondence with her through Chanut, the French ambassador 

 to Sweden, to whom he sent a dissertation on Love, which was 

 intended for her. He followed this with an essay on the Chief 

 Good, addressed directly to the queen. Finally, she invited Des- 

 cartes to go to Sweden and give her lessons in philosophy. Des- 

 cartes acceded to the request after considerable hesitation. He 

 reached Stockholm in October, 1649. The queen was very exact- 

 ing in her demands on the philosopher, and required, among 

 other things, that he attend upon her every morning at five 

 o'clock. The hardship of this duty, which did violence to his 

 life-long habit of lingering in bed, with other incidents of his 

 life at the Swedish capital, combined with the rigor of the 

 winter climate, were too much for Descartes, and entailed upon 

 him a pneumonia, from which he died. 



The written works of Descartes were collected and published 

 in Latin in 1670-^83. A selection from them was published in 

 Paris in 1843, and a collection of his moral and philosophical 

 works in 1855. 



The earliest work was the Discourse on the Method of Reason- 

 ing Well and Seeking the Truth in Science, which, besides the 

 exposition of general principles, according to the description in 

 the title, contains treatises on Dioptrics, Meteors, and Geometry, 

 the general scope of which is indicated by their titles. The cen- 

 tral propositions of the whole Discourse, according to Prof. Hux- 

 ley, are : " There is a path that leads to truth so surely that any 

 one who follows it must needs reach the goal, whether his capacity 

 be great or small. And there is one guiding rule by which a man 

 may always find this path and keep himself from straying when 

 he has found it. This golden rule is, Give unqualified assent to 

 no proposition but those the truth of which is so clear and dis- 



