Another important implication that [the Life Span] chapter held for Nichiren was indeed this very possibility of realizing the buddha land in the present world. In the “Parable” chapter of the Lotus Sūtra, Śākyamuni describes the world as a “burning house” in which there is no safe place. But now in the “Lifespan” chapter, having revealed his true identity as the primordially awakened buddha, Śākyamuni declares that, even in the fire that destroys the world at the end of the cosmic cycle, his land — the present world — is “tranquil” and “never decays”; it is a place where sentient beings are “joyful.” This is the realm depicted on Nichiren’s mandala. Alluding to this sūtra passage, Nichiren writes, “Now the Sahā world of original time is the constantly abiding pure land, liberated from the three disasters and beyond the [cycle of the] four kalpas [eons]. Its buddha has not already entered nirvana in the past, nor is he yet to be born in the future. And his disciples are of the same essence. This [reality] … is the three thousand realms of one’s own mind.”

Medieval Japanese Tendai thinkers of various teaching lineages shared a loose consensus that the enlightenment of the primordial Śākyamuni Buddha was “hidden in the depths” of the “Lifespan” chapter and could be accessed through the practitioner’s “mind contemplation” or “mind discernment” (J. kanjin). Kanjin in the Tiantai/Tendai tradition was originally a broad term for practice, in contrast to doctrinal study. Though interpretations varied, by Nichiren’s time, kanjin had come to mean the essence of the Tendai Lotus teachings and was often associated specifically with the “Lifespan” chapter. For Nichiren, now in the mappō era, the “mind discernment” that opens the primordial buddha’s awakening to all people is the chanting of Namu Myōhō-renge-kyō. He took the daimoku to be the “good medicine” that the excellent doctor leaves for his children in the “Lifespan” chapter’s narrative. In his reading, this chapter’s revelation of the primordial buddha’s constant presence in this world immediately collapses all temporal and spatial separation between the Buddha and the devotee. “Two thousand years and more have passed since the Buddha entered nirvāṇa,” he wrote. “But for those who embrace the Lotus Sūtra, at each day, each hour, each moment, the Buddha’s voice reaches them, conveying to them the message, ‘I do not die.’ ” Through chanting the daimoku, the timeless realm of the Buddha’s original enlightenment is retrieved in the present moment; ordinary people manifest buddhahood just as they are, and their world becomes the buddha land.

“In terms of realizing buddhahood with this very body,” Nichiren wrote, “the trace teaching is the gate that affords entry, while the origin teaching holds its true meaning, that is, its actualization.” Where the trace teaching presents buddhahood as a potential inherent in the nine realms of unenlightened beings, the origin teaching shows the buddha realm revealed through the Buddha’s conduct in the nine realms, represented in particular by the bodhisattva realm. The buddha realm has no separate existence or mode of expression apart from the nine realms. Rather, the nine realms, without losing their individual character, are purified, elevated, and positively redirected in the light of the realized buddha realm. This is the awakened reality of the Buddha, which Nichiren termed “the single thought-moment comprising three thousand realms in actuality” (ji no ichinen sanzen). For him, this revelation had one sole scriptural locus: it was “hidden in the depths” of the “Lifespan” chapter of the origin teaching of the Lotus Sūtra.

The interpenetration of ten realms reveals that, in principle, there is no difference between an ordinary person and a buddha; both embody the three thousand realms in a single thought-moment. But in ordinary, deluded persons the buddha realm remains dormant and unrealized, and they are trapped by suffering. In the case of a buddha, the buddha realm is fully expressed; that is, all the other nine realms are illuminated, elevated, and redirected by it to work in an enlightened way. For Nichiren, this fully realized state was embodied in the daimoku. We could say that chanting the daimoku aligns or “syncs” the ten realms and three thousand realms of the practitioner with those of the Buddha, enabling direct realization in the very act of practice.

Nichiren took the ichinen sanzen concept that Zhiyi had briefly delineated and made it the foundation of his teaching. For Nichiren, ichinen sanzen was “the father and mother of the buddhas.” He often referred to it in its “short form,” so to speak, as the mutual inclusion of the ten dharma realms… . Because the “ten suchnesses” (referred to at the beginning of the “Skillful Means” chapter) and the mutual inclusion of the ten realms are both concepts integral to the single thought-moment that is three thousand realms, the one implied the other, and Nichiren could take “the real aspect of all dharmas” or the ten suchnesses as pointing to the mutual inclusion of the ten realms. For him, this teaching was unique to the Lotus Sūtra and was what qualified it as the “wonderful dharma.” In one passage, he writes: “The sūtras that the Buddha preached for more than forty years before the Lotus do not set forth the mutual inclusion of the ten realms. And because they do not set forth the mutual inclusion of the ten realms, one cannot know the buddha realm within one’s own mind, and because one does not know the buddha realm within one’s own mind, the buddhas do not manifest externally either. … But now with the Lotus Sūtra, the buddha realm within the nine realms was opened, and those who had heard the Buddha’s forty and more years of preaching — bodhisattvas, persons of the two vehicles, and ordinary beings of the six paths — could for the first time see the buddha realm within themselves.”