Elisabeth of Bohemia

Elisabeth was the eldest daughter of the Winter King, Frederick V, and lived in exile in The Hague. She studied mathematics, languages, and philosophy. In 1643 she wrote to Descartes asking how an immaterial mind could cause physical movement. Her question exposed the deepest weakness of Cartesian dualism. Descartes tried to answer her and failed. Their correspondence, which continued until his death, covers not only metaphysics but ethics, the passions, and the good life. She eventually became Abbess of Herford in Germany. She is the reason we know that Descartes' system had a crack at its center.