Adi Shankara was an intellectual giant, a genius of linguistics, and above all, a spiritual light and the pride of India. The level of wisdom and knowledge he showed at a very early age made him a shining light for humanity. Shankara was a philosopher and theologian, most renowned exponent of the Advaita Vedanta school of philosophy, from whose doctrines the main currents of modern Indian thought are derived. He wrote commentaries on the Brahma-sutra, the principal Upanishads, and the Bhagavadgita, affirming his belief in one eternal unchanging reality (brahman) and the illusion of plurality and differentiation.