Perennialism, also referred to as Perennial Philosophy and Perennial Wisdom, is a general idea in philosophy and spirituality which posits that the recurrence of common themes across world religions, cultures, and other aspects of human society, regardless of origin, illuminate a timeless, universal truth about the nature of reality, humanity, ethics, and consciousness. Some perennialists emphasise common themes in religious experiences and mystical traditions across time and culture, while others argue that religious traditions share a single, metaphysical truth or origin from which all esoteric and exoteric knowledge and doctrine has grown.