The "Discours de la méthode," published anonymously in 1637, is regarded as the first and most influential manifesto of modern rationalism and scientific methodological awareness. More noteworthy than the four rules presented by Descartes, which he highlights as the fundamental principles for the methodical attainment of true knowledge, is the autobiographical perspective from which the author seeks to engage a broad audience to follow him on his journey. This journey led him to the discovery of a universal scientific method and metaphysical principles of all sciences based solely on autonomous reason. The new edition offers not only the French text and a completely newly created German translation but also the early dream narrative "Olympica," translated into German for the first time, as well as the late letter to Picot, which was prefixed to the 1647 French edition of the "Principia philosophiae." Both provide important testimonies of Descartes' self-explanation. By including these supplements, the volume spans from Descartes' earliest texts from 1619 through the "Discours" of 1637 to the "Principes" of 1647, thus documenting the stages of the development of his thought. The editor's introduction aims to clarify how Descartes' programmatic approach can be assessed from the outside, what determined the development of this thought from the inside, and what Descartes chose to conceal from us.