In the fourth month of the ninth year of Bun’ei (1272), Shijō Kingo traveled from Kamakura to Sado Island to visit Nichiren Daishonin. Kingo was a samurai who served the Ema family, a branch of the ruling Hōjō clan. The journey to Sado was a long, arduous one, involving a boat trip across the Sea of Japan, and required that he absent himself from his duties in Kamakura for more than a month. In the fifth month of the same year, soon after Shijō Kingo returned to Kamakura, Nichiren Daishonin sent him this letter. It was written in gratitude for the samurai’s visit. In the letter, the Daishonin explains the power of Nam-myoho-renge-kyo in terms of such profound Buddhist principles as the fusion of reality and wisdom, and earthly desires are enlightenment. Although Hinayana Buddhism teaches that earthly desires must be eliminated to attain enlightenment, Mahayana, and particularly the Lotus Sutra, teaches that earthly desires are one with and inseparable from enlightenment. The reason is that both are the workings, or expression, of life itself, and thus are the same in their source. Nichiren Daishonin teaches that, when one bases one’s life on Nam-myoho-renge-kyo, earthly desires work naturally for one’s own and others’ happiness. The great power of Nam-myoho-renge-kyo, which is inherently positive and creative, directs the great energy of one’s earthly desires toward happiness and value for all. Thus, when one chants the daimoku, “earthly desires are enlightenment.” Until his near-execution at Tatsunokuchi in the ninth month of 1271, the Daishonin had assumed the role of Bodhisattva Superior Practices, the votary whose appearance is predicted in the Lotus Sutra. He had spent all his time teaching the essence of the sutra and propagating the faith. After Tatsunokuchi, he revealed his true identity as the Buddha who is one with the supreme Law of Nam-myoho-renge-kyo. In this letter, the Daishonin teaches the significance of the daimoku from the standpoint of the Buddha who opens the way to Buddhahood for all humankind. He first states that it is his great joy to meet persecutions as the votary of the Lotus Sutra, because it is the sure way to attain Buddhahood. “Though the teaching I am now propagating seems limited, it is extremely profound. That is because it goes deeper than the teaching expounded by T’ien-t’ai, Dengyō, and others.” He reveals that the ultimate Law of all Buddhas is none other than Nam-myoho-renge-kyo. https://www.nichirenlibrary.org/en/wnd-1/Content/35