The Vedic era conceptualization of the divine or the One, states Jeaneane Fowler, is more abstract than a monotheistic God, it is the Reality behind and of the phenomenal universe. The Vedic hymns treat it as "limitless, indescribable, absolute principle", thus the Vedic divine is something of a panentheism rather than simple henotheism. In late Vedic era, around the start of Upanishadic age (c. 800 BCE), theosophical speculations emerge that develop concepts which scholars variously call nondualism or monism, as well as forms of non-theism and pantheism. An example of the questioning of the concept of God, in addition to henotheistic hymns found therein, are in later portions of the "Rigveda", such as the Nasadiya Sukta. Hinduism calls the metaphysical absolute concept as Brahman, incorporating within it the transcendent and immanent reality. Different schools of thought interpret Brahman as either personal, impersonal or transpersonal. Ishwar Chandra Sharma describes it as "Absolute Reality, beyond all dualities of existence and non-existence, light and darkness, and of time, space and cause".