The Recoverer of the Prabandham
Nāthamuni (c. 823–923 CE) is one of the most pivotal figures in Śrī Vaiṣṇava history. The 4,000 verses of the Āzhvārs (Divya Prabandham) had been largely forgotten after the Āzhvārs' own lifetimes. Nāthamuni, upon hearing a partial recitation of Nammāzhvār's Kanninuṃ Cirutambu at Śrīraṅgam, was so moved that he set out to recover the complete Prabandham.
The Recovery
Nāthamuni meditated for years at Āzhvārtirunagari (Nammāzhvār's birthplace) and, in a state of divine vision, received all 4,000 verses directly from Nammāzhvār himself. He then organized them into four parts (Nālāyira Divya Prabandham) and established their canonical recitation at temples — a practice that continues to this day.
Philosophical Contributions
Nāthamuni is credited with composing Nyāyatattva and Yogarahasya — works on Viśiṣṭādvaita philosophy and yoga that are largely lost but whose existence is referred to in later texts. He is also credited with the annual Adhyayanotsavam festival at Śrīraṅgam, where the Divya Prabandham is recited for 21 days.
Founder of the Organized Tradition
Before Nāthamuni, the Āzhvārs' devotion was intense but not fully organized as a systematic tradition. Nāthamuni established the paramparā as a living institution, transmitted the teaching to his grandson Yāmunācārya (Āḷavandhār), and set the template for organized Śrī Vaiṣṇava practice that Rāmānuja would later expand.