Today is the birthday of Rene Descartes. People usually remember him for saying, "Je pense donc je suis." (I think therefore I am.) For me, his most important accomplishment was identifying the relationship between geometry and algebra, thus laying the foundation for analytical geometry. Cartesian coordinates are named after him, although he did not carry his mathematical research far enough to plot a line.
May. 18, 2013: The Writer's Almanac
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