Dualism is any religious or philosophical system characterized by a fundamental opposition of two independent or complimentary principles. Among religious dualisms are the unending conflict of good and evil spirits envisaged in Zoroastrianism and the opposition of light and darkness in Jewish apocalyptic, Gnosticism, and Manichaeism. The Chinese complimentary principles of ying and yang exemplify a cosmological dualism while the mind-body dualism of Descartes is the best-known philosophical type. Dualism is often opposed to monism and pluralism.