In late 1633, as Descartes was preparing The World and Man for publication, he learned that Galileo had been condemned by the Catholic Church for defending the motion of the earth. His reaction to the news was swift and powerful: as his own treatises also espoused the proposition deemed heretical, he canceled their publication. More than thirty years after Descartes had begun his project, these works were finally published, posthumously, both to acclaim and to controversy. Together, they profoundly influenced the course of modern philosophy. This volume presents Roger Ariew's clear and engaging translations of Descartes's treatises, along with a general Introduction, describing the long road to publication, the reception of the works, and their significance. Appendices provide selections from Descartes's correspondence on Galileo, Part V of the Discourse on Method, and a summary of Descartes's Description of the Human Body.