The idea of mystical union with God or a higher being is universal in theological systems, although it may take many forms, metaphorical and moral as well as metaphysical. In Hinduism this concept is expressed in the saying Tat twam asi (“This is thou”); a human being, by finding his or her true immortal self (atman), becomes united with Brahman and, in so doing, achieves nirvana. In Buddhism, similarly, humans must strive to recognize the unity of all within the eternal Buddha, the dharmakaya, the absolute truth or reality that transcends human perception. Jewish mysticism teaches devekut, commonly translated as adhesion, cleaving, or union with God. Christian mysticism refers to Jesus' words “Abide in me and I in you” (John 15:4) as pertaining to divine union, which has its concrete expression in baptism and the Eucharist. Even Islam, which insists on the absolute transcendence of God, has developed the mystical doctrine of tawhid (“union”).