"I am accustomed to sleep and in my dreams to imagine the same things that lunatics imagine when awake. "

Rene Descartes was born on 31st March 1596 in Indre-et-Loire, France. In 1618, Descartes joined the International College of War, of Maurice of Nassau in the Dutch Republic. On 10 November 1618, while walking through Breda, Descartes met Isaac Beeckman, who sparked his interest in mathematics and the new physics, particularly the problem of the fall of heavy bodies. While in the service of the Duke Maximilian of Bavaria, Descartes was present at the Battle of the White Mountain outside Prague, in November 1620.

In 1622 he returned to France, and during the next few years spent time in Paris and other parts of Europe. He arrived in La Haye in 1623, selling all of his property, investing this remuneration in bonds which provided Descartes with a comfortable income for the rest of his life. Descartes was present at the siege of La Rochelle by Cardinal Richelieu in 1627.He returned to the Dutch Republic in 1628, where he lived until September 1649.

In April 1629 he joined the University of Franeker, living at the Sjaerdemaslot, and the next year, under the name "Poitevin", he enrolled at Leyden University to study mathematics with Jacob Golius and astronomy with Martin Hortensius. While in the Netherlands Descartes frequently moved around and wrote all of his major works during this time.

In 1633, Galileo was condemned by the Roman Catholic Church, and Descartes abandoned plans to publish Treatise on the World, his work of the previous four years. Discourse on the Method was published in 1637. In it Descartes lays out four rules of thought, meant to ensure that our knowledge rests upon a firm foundation. Descartes continued to publish works concerning both mathematics and philosophy for the rest of his life.

Descartes was a major figure in 17th-century continental rationalism, later advocated by Baruch Spinoza and Gottfried Leibniz, and opposed by the empiricist school of thought consisting of Hobbes, Locke, Berkeley, Jean-Jacques Rousseau, and Hume. Leibniz, Spinoza and Descartes were all well versed in mathematics as well as philosophy, and Descartes and Leibniz contributed greatly to science as well. As the inventor of the Cartesian coordinate system, Descartes founded analytical geometry, the bridge between algebra and geometry, crucial to the discovery of infinitesimal calculus and analysis.

He is best known for the philosophical statement "Cogito ergo sum" (French: "Je pense donc je suis"; English: "I think, therefore I am"). Descartes died on 11th February 1650 in Stockholm, Sweden where he had been invited as a teacher for Queen Christina of Sweden.


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