Near the close of the Mahābhārata-tātparya-nirṇaya, a Sanskrit poem of some five thousand verses that retells the great epic, its author makes a claim about himself. When 4,300 years of the present age, the Kali age, had passed, the poem says, Bhīma was born again on earth in the body of a Brahmin, to make known the truth about Vishnu that demons had hidden. The poem treats Bhīma, the strongest of the epic's five brothers, as a descent of Vāyu, the wind god who serves Vishnu, and earlier names the third such descent Pūrṇaprajña. Pūrṇaprajña is one of the names of Madhva, the poem's author and the founder of Dvaita, the dualist school of Vedānta, the philosophy built on the Upanishads. In its last verses he signs as Ānandatīrtha, also called Pūrṇaprajña, and says he composed it at the bidding of Nārāyaṇa, a name of Vishnu, at Badarī in the Himalayas.
The hidden truth fits in one sentence: God, souls and the material world are really and permanently different, and no scripture teaches otherwise. Everything other than God depends on him, and that dependence is what keeps it distinct from him. Advaita, the non-dualism of the earlier teacher Śaṅkara, held that the self is Brahman, the ultimate reality, and the world of many things an appearance. Against it Madhva set five differences that never dissolve: between God and souls, God and matter, soul and matter, one soul and another, and one piece of matter and another. Advaita read the Upanishadic sentence tat tvam asi, "you are that", as an identity. Madhva divided it differently, carrying a vowel over from the word before, so that it reads atat tvam asi: "you are not that".
His life is known mainly from the Madhvavijaya, a verse biography in sixteen cantos composed in the fourteenth century by Nārāyaṇa Paṇḍitācārya, the son of one of Madhva's own disciples. The tradition takes the poem's 4,300 years as the year of his birth, 1199 by its reckoning, and it dates his death to 1278. Most modern reference works place him later, at about 1238 to 1317. He was born at Pājaka, near Udupi on the coast of what is now Karnataka, into a Brahmin family, and was named Vāsudeva. The tradition says that as a teenager he became a renouncer in an Advaita monastery at Udupi under the teacher Acyutaprekṣa, disputed with him over the meaning of scripture, and went his own way. The tradition also counts Vyāsa, the sage to whom the Brahma Sūtras and the Mahābhārata are ascribed, as his teacher, and says Madhva met him at Badarī before writing his commentary on the Sūtras.
His argument rested on trust in ordinary knowing. If perception were wrong about something as plain as our separateness from one another and from God, nothing perceived could be trusted, the words of the Vedas included, since they reach a reader only through the senses and inference. Scripture tells what perception and inference cannot reach — the nature of the self and of God — but it cannot contradict them.
The doctrine of difference cut against Rāmānuja as well, the Vaiṣṇava teacher of the Tamil south whose qualified non-dualism, Viśiṣṭādvaita, had already made the world real and God personal. Rāmānuja held that souls share God's essential nature and that every freed soul enjoys the same bliss. To Madhva any identity of soul and God compromised Vishnu's supremacy and emptied devotion of its point. Souls differ by nature, he taught, in a rank that holds even in liberation: some are fit for release, some are reborn without end, some are bound for darkness. Karma does not make a soul what it is; it carries each soul toward the end its nature already holds. Only Vishnu's grace, answering devotion, frees anyone.
Rivals answered for centuries. In the sixteenth century the Advaita scholar Appayya Dīkṣita accused him of citing scriptural passages found nowhere else. Roque Mesquita, an Indologist at Vienna, concluded that Madhva composed those passages himself in the belief that they were revealed to him; Dvaita scholars, among them B. N. K. Sharma, the school's modern historian, contest it. Inside the school his arguments were carried on by Jayatīrtha in the fourteenth century and by Vyāsatīrtha, whose Nyāyāmṛta drew from the Advaita side its most celebrated later reply, Madhusūdana Sarasvatī's Advaitasiddhi.
Some thirty-seven works are credited to Madhva, among them commentaries on the Upanishads, the Bhagavadgītā and the Brahma Sūtras, and the verse Anuvyākhyāna, which accompanies the last. Three of his shorter works are held here: the Aṇubhāṣya, his reading of the Brahma Sūtras pressed into some thirty verses; the Pramāṇalakṣaṇa, a short treatise on the means of valid knowledge; and the Kṛṣṇāmṛtamahārṇava, an anthology of about 230 verses on the worship of Vishnu. At Udupi he founded a temple of Krishna, and it is still in the charge of monks in succession from his disciples, drawn from eight monasteries around it.