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 utterances of Descartes's disciple, Regius, resulted in Descartes being summoned before the magistrates of Utrecht on charges of irreligion 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 Cartesianism 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 Descartes to go to Sweden and give her lessons in philosophy. Descartes acceded to the request after considerable hesitation. He reached Stockholm in October, 1649. The queen was very exacting 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 Reasoning 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 central propositions of the whole Discourse, according to Prof. Huxley, 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-
