Between the years 1643 and 1649, Princess Elisabeth of Bohemia (1618-80) and Ren Descartes (1596-1650) exchanged fifty-eight letters--thirty-two from Descartes and twenty-six from Elisabeth. Their correspondence contains the only known extant philosophical writings by Elisabeth, revealing her mastery of metaphysics, analytic geometry, and moral philosophy, as well as her keen interest in natural philosophy. The letters are essential reading for...