The Metaphysics of Quality (MOQ) is a theory of reality introduced in Robert M. Pirsig's philosophical novel, Zen and the Art of Motorcycle Maintenance (1974) and expanded in Lila: An Inquiry into Morals (1991). The MOQ incorporates facets of Sophism, East Asian philosophy, pragmatism, the work of F. S. C. Northrop, and indigenous American philosophy. Pirsig argues that the MOQ is a better lens through which to view reality than the subjective/objective mindset that Pirsig attributes to Aristotle. Zen and the Art of Motorcycle Maintenance references the Sanskrit doctrine of Tat Tvam Asi ("Thou art that"), which asserts an existential monism as opposed to the subject–object dualism.