This letter was written at Ichinosawa on Sado Island in the fifth month, 1273, to Gijō-bō, who had been the Daishonin’s senior at Seichō-ji temple in Awa Province. Nearly a month earlier, Nichiren Daishonin had written The Object of Devotion for Observing the Mind, in which he had explained both the object of devotion in terms of the Law and the correct practice for attaining enlightenment in the Latter Day. This letter briefly restates the profound contents of The Object of Devotion for Observing the Mind. Nichiren Daishonin says that, of all the chapters of the Lotus Sutra, the “Life Span” chapter is particularly important to him. He quotes a passage, “ . . . single-mindedly desiring to see the Buddha . . . ,” and notes, “As a result of this passage, I have revealed the Buddhahood in my own life.” He declares that in his capacity as the Buddha of the Latter Day of the Law he has realized and embodied Nam-myoho-renge-kyo of the Three Great Secret Laws, which is implied in the depths of the “Life Span” chapter. This is one of the earliest references in his writings to the Three Great Secret Laws: the invocation (Nam-myoho-renge-kyo), the object of devotion (the Gohonzon), and the place of worship (the sanctuary). https://www.nichirenlibrary.org/en/wnd-1/Content/41