Madhva began his school after his Upanayana at age seven, and became a monk or Sannyasi in his teenage, although his father was initially opposed to this. He joined an Advaita Vedanta monastery in Udupi (Karnataka), accepted his guru to be Achyutrapreksha, who is also referred to as Achyutraprajna in some sources. Madhva studied the Upanishads and the Advaita literature, but was unconvinced by its nondualism philosophy of oneness of human soul and god, had frequent disagreements with his guru, left the monastery, and began his own Dvaita movement based on dualism premises of Dvi - asserting that human soul and god (as Vishnu) are two different things. Madhva never acknowledged Achyutrapreksha as his guru or his monastic lineage in his writings. Madhva is said to have been clever in philosophy, and also to have been tall and strongly built.