Roger Ariew presents a new account of Descartes as a philosopher who sought to engage his contemporaries and society. He argues that the Principles of Philosophy was written to rival Scholastic textbooks, and considers Descartes' enterprise in contrast to the tradition it was designed to replace and in relation to the works of the first Cartesians.

Descartes and the last Scholastics: objections and replies -- Descartes and the Scotists -- Ideas, before and after Descartes -- The Cartesian destiny of form and matter -- Descartes, Basso, and Toletus: three kinds of Corpuscularians -- Scholastics and the new astronomy on the substance of the heavens -- Descartes and the Jesuits of La Fleche: the Eucharist -- Condemnations of Cartesianism: the extension and unity of the universe -- Cartesians, Gassendists, and censorship -- The cogito in the seventeenth century.