There are various sub schools of Vedanta, like Advaita Vedanta (non-dual), Vishishtadvaita and Bhedabheda Vedanta (difference and non-difference). The schools of Vedanta all attempt to explain the nature and relationship of Brahman (universal soul or Self) and Atman (individual self), which they see as the central topic of the Vedas. One of the earliest attempts at this was Bādarāyaņa's Brahma Sutras, which is canonical for all Vedanta sub-schools. Advaita Vedanta is a major sub school of Vedanta which holds a non-dual Idealistic metaphysics. According to Advaita thinkers like Adi Shankara (788–820) and his contemporary Maṇḍana Miśra, Brahman, the single unitary consciousness or absolute awareness, appears as the diversity of the world because of "maya" or illusion, and hence perception of plurality is "mithya", error. The world and all beings or souls in it have no separate existence from Brahman, universal consciousness, and the seemingly independent soul ("jiva") is identical to Brahman. These doctrines are represented in verses such as "brahma satyam jagan mithya; jīvo brahmaiva na aparah" (Brahman is alone True, and this world of plurality is an error; the individual self is not different from Brahman). Other forms of Vedanta like the Vishishtadvaita of Ramanuja and the Bhedabheda of Bhāskara are not as radical in their non-dualism, accepting that there is a certain difference between individual souls and Brahman. Dvaita school of Vedanta by Madhvacharya maintains the opposing view that the world is real and eternal. It also argues that real atman fully depends and reflection of independent brahman. The Tantric tradition of Kashmir Shaivism has also been categorized by scholars as a form of Idealism. The key thinker of this tradition is the Kashmirian Abhinavagupta (975–1025 CE). Modern Vedic Idealism was defended by the influential Indian philosopher Sarvepalli Radhakrishnan in his 1932 "An Idealist View of Life" and other works, which espouse Advaita Vedanta. The essence of Hindu Idealism is captured by such modern writers as Sri Nisargadatta Maharaj, Sri Aurobindo, P. R. Sarkar, and Sohail Inayatullah.