Discourse on Method is a philosophical and autobiographical work by the French philosopher René Descartes. It was published in 1637 and is considered one of the most influential works in the history of modern Western philosophy.

The main purpose of Discourse on Method is to outline Descartes' method of systematic doubt and his search for certain knowledge. Descartes was skeptical of traditional sources of knowledge, such as authority, tradition, and sensory experience, and believed that true knowledge could only be obtained through reason and intuition.

In the work, Descartes also presents his famous dictum "Cogito, ergo sum" ("I think, therefore I am"), which he uses as the starting point for his philosophy. He argues that the very act of thinking proves one's existence, and that this provides a firm foundation for all knowledge.

Discourse on Method is also notable for its contributions to the development of analytical geometry, as Descartes uses his method to develop a new system of algebraic notation and a way to graph equations.

Overall, Discourse on Method is an important work in the history of philosophy and science, and its influence can still be seen in contemporary debates about the nature of knowledge and the role of reason in human understanding.