' SKETCH OF RENE DESCARTES. 835 



tant princes. While in garrison .at Breda, he saw one day a pla- 

 card in Flemish to which the attention of a considerable crowd 

 had been attracted. It was the statement of a mathematical 

 problem, to which the author, after the fashion of the times, 

 invited solutions. Not understanding the language in which it 

 was written, Descartes asked one of the bystanders to translate 

 it to him. This man was Beeckman, Principal of the College of 

 Dort, himself a mathematician. Surprised to find a young soldier 

 interested in such a matter, Beeckman explained the terms of the 

 challenge with his most learned air. Descartes said at once that 

 he would solve the problem, and brought the solution to Beeck- 

 man on the next day, having mastered it in less than an hour. 

 The winter of 1619 was spent in quarters at Neuburg, on the Dan- 

 ube, to a large extent in study, and was, according to Dr. William 

 Wallace, in the Encyclopaedia Britannica, the critical period of 

 Descartes's life. "Here, in his warm room, he indulged those 

 meditations which afterward led to the Discourse on Method. It 

 was here that, on the eve of St. Martin's day, he { was filled with 

 enthusiasm, and discovered the foundations of a marvelous sci- 

 ence/ He retired to rest with anxious thoughts of his future 

 career, which haunted him through the night in three dreams, 

 that left a deep impression on his mind. ' Next day/ he continues, 

 ' I began to understand the first principles of my marvelous dis- 

 covery/ " In the next year he sought out the Rosicrucians, to 

 obtain some knowledge of their supposed mystical wisdom, but 

 without success. Descartes retired from military life upon the 

 defeat and death of Count Bucquoy at the hands of Bethlen 

 Gabor's revolted Hungarians in 1621. 



During his career in the army, Descartes composed a Latin 

 treatise on music, which he intrusted to Beeckman. It was sur- 

 reptitiously copied, and was published without the knowledge of 

 the author in 1618. It seems to have been considerablv successful, 

 and was reprinted several times and translated into English and 

 French. But Beeckman's treachery cost him Descartes's friend- 

 ship. Among other writings of this period, unpublished or lost, 

 but mentioned in the catalogue prepared by Chanut on the order of 

 Queen Christina of Sweden, are General Considerations on Science ; 

 a fragment on Algebra ; Democritia, or Fugitive Thoughts ; Ex- 

 periments, or a Collection of Observations; and a collection of 

 mathematical speculations entitled Parnassus. Descartes contin- 

 ued his travels in a private way, having in view, as he expressed 

 his purpose, to look into the courts of princes, to become acquaint- 

 ed with men of different humors and different conditions, to in- 

 form himself concerning the natural products of different climates 

 and the various civil usages and customs observed among differ- 

 ent peoples ; and to seek in the great book of the world knowl- 



