René Descartes was a French philosopher, mathematician, and scientist who spent a large portion of his working life in the Dutch Republic. Descartes is widely regarded as one of the founders of the Enlightenment which launched modern philosophy. 

Many elements of Descartes's philosophy have precedents in revived Stoicism. In the opening section of the Passions of the Soul, an early modern treatise on emotions, Descartes goes so far as to assert that he will write on this topic "as if no one had written on these matters before." His best known philosophical statement is "cogito, ergo sum" ("I think, therefore I am”.)

In the 17th-century Dutch Republic, the rise of early modern rationalism exerted a profound influence on modern Western thought in general. The 17th-century rationalists like Descartes, Spinoza and Leibniz  give the "Age of Reason" its name and place in history. Leibniz, Spinoza, and Descartes were all well-versed in mathematics as well as philosophy. Descartes's Meditations on First Philosophy (1641) continues to be a standard text at most university philosophy departments and he is credited as the father of coordinate geometry, the bridge between algebra and geometry. 

TRY THIS!

Pretend you’re a philosopher and write one or two easy-to-understand sentences that explain this quotation from Descartes. Ask the class (or your friends) to choose the one they think best expresses his meaning.