Madhvācārya—a great thirteenth-century Vaiṣṇava spiritual master, who preached the theistic philosophy of pure dualism. The founder of the dvaita school of Vedānta philosophy. He wrote a number of works which refuted the impersonal philosophy of Śaṅkarācārya. He appeared in the 13th century in Udipī, in South India. He took sannyāsa at the age of twelve, traveled all over India and had the personal darśana of Śrīla Vyāsadeva in the Himalayan abode of Badarikāśrama and presented his commentary on Bhagavad-gītā before that venerable sage. He also received a śālagrama-śīla called Aṣṭamūrti from Vyāsa. He was very powerful both physically and intellectualy, and was considered to be an incarnation of Vāyu, the wind god.