Adi Shankara (ca. 788-820 A.D.)Adi Shankara (ca. 788-820) - He is perhaps Hindu's most famous apologist.  At a time when Islam and Buddhism were spreading throughout India, Adi Shankara wrote vigorously in defense of Hinduism, and established the doctrine known as advaita, which was his attempt to develop a unifying theme among the more than 200 existing Upanishads.  He also wrote numerous commentaries on the Vedic canon (Hindu scriptures), including the Bhagavad Gita, in order to support the doctrine of advaita.  Adi Shankara (whose name means "bestower of happiness" in Sanskrit) was born in Southern India in the town of Kaladi (in present-day Kerala) during the time of the Chēra dynasty.  According to legend, his parents had been childless for a long time, so they went to the Vadakkunnathan Temple and prayed.  Each had a dream in which they were given the choice to either have a son who would live a long uneventful life, or a son who would live a short extraordinary life.  Both chose the latter.  True to the dream, he showed a remarkable aptitude for learning at a very young age.  Because of his penchant for arguing in favor of Hinduism from an intellectual standpoint, among Westerners familiar with his work, he is often called the "Thomas Aquinas of Hindu thought" .  His work is considered essential reading for followers of Hinduism; however, it is not universally accepted among Hindus, and the primary competing school of thought is known as Mīmāṃsā.  Adi Shankara traveled extensively throughout India and established four Hindu monasteries.  True to his parents dream, he lived only 32 years, though the cause of his death is not known.  Because of this, the belief developed among his followers that he attained videha mukti, which is a state of the spirit being freed from the body.  What is known about his last days is that he was in Northern India near the Himalayan region.