 By the time of the Lettre sur les aveugles (1749), Diderot has launched upon a philosophical project, or a set of intersecting projects, which will endure to the end of his life: a radicalization of empiricism in the direction of a materialist metaphysics, which also remains at times skeptical or at least anti-foundationalist with regard both to the possibility of an intellectual system, and to the existence of order or totality in the universe.