Discourse on Method (1636)

Discourse on Method was published in 1636. Although he had dedicated his adult life to research in philosophy, mathematics, and science, the 40-year-old Descartes had not published anything prior to it—largely due to fears of censure. Discourse on Method introduces the scientific method that Descartes invented, explains how his views came about, and describes why he has been so hesitant to publish. In addition to its insight into Descartes's philosophy and method, it also gives us insight into the intellectual climate of his time.

Meditations on First Philosophy (1641)

Meditations on First Philosophy is considered by many scholars to be the starting point of modern Western philosophy. The meditations are a series of philosophical reflections in which Descartes methodically examines the nature of knowledge, reality, and the self. The work was written during the Scientific Revolution and took part in the emergence of new ways of thinking. In this one brief work, Descartes turned key Aristotelian doctrines upside down and framed many of the questions that philosophers would debate for centuries to come. While we can trace Descartes’s enormous influence to the development of mind-body dualism and modern skepticism, he also provided the Cartesian Circle, the Wax Argument, as well as his theories of ideas, of body, and of perception—all of which became important seeds for philosophical debate. 

Rules for the Direction of the Mind (1701)

Rules for the Direction of the Mind (Regulae ad directionem ingenii in Latin) is a work by René Descartes that was published posthumously. It is described in a section of summary and analysis in the SparkNotes Guide Selected Works of René Descartes.