What is the novel of René Descartes?

René Descartes is primarily known for his work in philosophy and mathematics, rather than for a novel. His most famous philosophical work is "Meditations on First Philosophy," where he explores foundational questions about existence, knowledge, and the nature of reality. Descartes is often regarded as the father of modern philosophy due to his method of systematic doubt and emphasis on reason. If you meant to refer to a specific philosophical text or concept instead of a novel, please clarify!