Sikhism is an ethical monotheism fusing elements of Hinduism and Islam. It was founded by Guru Nanak (1469-1539), a mystic who believed that God transcends religious distinctions. Sikhism stresses the unity, truth, and creativity of a personal God and urges union with him through meditation and surrender to his will. It rejects the Hindu caste system, priesthood, image worship, asceticism, and pilgrimage, although it retains the Hindu doctrines of transmigration and karma. The ultimate spiritual authority is the Adi Granth, a collection of hymns and devotional poetry. The Golden Temple in Amritsar is the religious center.