‘A New Logic’ points out that the Dioptrics, Meteors, and Geometry were not free-standing treatises but advertisements for a novel method of reasoning in the sciences. The Discourse on Method was outwardly the autobiography of an unspecified intellectual and did little more than hint at the workings of the method the book was about. Descartes hoped the potential of the method would be evident from his general explanation of it and from its applications in the Essays. He was over-optimistic. The Essays proved controversial and his explanation of the method struck some readers as skimpy and question-begging. He eventually saw the need to fill the gaps with principles from metaphysics.