Honen, a Tendai-trained monk, broke from the establishment of his day in 1175 to teach that in the present degenerate age, mappo, ordinary people could not realistically complete the demanding meditative and monastic disciplines that had defined the path for centuries, and that the recitation of Amida Buddha's name, the nembutsu, Namu Amida Butsu, was itself sufficient, because it called on Amida's own vow rather than the practitioner's accumulated merit. Honen's Pure Land school, Jodo Shu, still held the nembutsu as a practice to be repeated with devotion and discipline.
Shinran, Honen's disciple, pushed the logic further after his own teacher's exile. In his major work, the Kyogyoshinsho, Shinran taught that a single sincere moment of entrusting oneself to Amida's vow, shinjin, was the actual point at which salvation was settled, and that repeating the nembutsu afterward was gratitude rather than a further contribution toward one's own liberation. Where Honen still left room for the nembutsu itself to be read as a discipline the practitioner performs, Shinran read it as Amida's working expressing itself through the practitioner, closing the gap almost entirely between a person's own effort and the power that saves them. Shinran's teaching became, after his death, the foundation of Jodo Shinshu, the True Pure Land school, now the largest Buddhist denomination in Japan.