This volume collects some of the seminal essays on Descartes by Daniel Garber, one of the preeminent scholars of early-modern philosophy. A central theme unifying the volume is the interconnection between Descartes's philosophical and scientific interests, and the extent to which these two sides of the Cartesian program illuminate each other, a question rarely treated in the existing literature. This collection will be a mandatory purchase for any serious student of or professional working in 17th-century philosophy, history of science, or history of ideas.