Search for Yoshiro Tamura on this website and you’ll find that he is “famous” for his views on Original Enlightenment. (He’s also one of the translators of Rissho Kosei-kai’s 1975 edition of The Threefold Lotus Sutra.)

The publisher’s description of Jacqueline Stone’s “Original Enlightenment and the Transformation of Medieval Japanese Buddhism” explains what’s meant by “original enlightenment”:

Original enlightenment thought (hongaku shiso) dominated Buddhist intellectual circles throughout Japan’s medieval period. Enlightenment, this discourse claims, is neither a goal to be achieved nor a potential to be realized but the true status of all things. Every animate and inanimate object manifests the primordially enlightened Buddha just as it is.

In Tamura’s “Introduction to the Lotus Sutra,” he explains original enlightenment in this way:

Saicho skillfully merged the Lotus Sutra’s comprehensive and unifying view of truth with the Flower Garland Sutra’s fundamental and purifying view of the truth. In his thought, the Lotus Sutra’s worldview, which encompasses the actual world, is united with the worldview of the Flower Garland Sutra, which shines with the ideal. This is a unity of the ideal and the actual. In further developments along this line, thinkers after Saicho combined typical Mahayana Buddhist ideas from the Lotus Sutra, the Flower Garland Sutra, the esoteric sutras, Zen, and so forth, eventually achieving the ultimate in philosophical theory—the Tendai doctrine of original enlightenment. The Tendai doctrine of original, innate or intrinsic, enlightenment is the culmination of Buddhism, subsuming all Buddhist teachings on the basis of Tendai Lotus Sutra doctrine. In general, it makes it clear that breaking through the bounds of right and wrong, good and evil, beauty and ugliness—human relative and dualistic thought and judgment—so thoroughly breaks through that barrier that it discloses a very different absolute and monistic world. Here, the boundary between heaven and earth vanishes, the distinction between above and below disappears, and only infinite cosmic space and eternal absolute time remain. From this standpoint, there is a radical affirmation that the actual world is like a dynamic pulsation of ideal light in which a moment is like an eternity. Life and death and everything else come to be affirmed as the activity of eternal life. Tendai doctrine includes such teachings as “The eternal sun and moon, today’s sun and moon, and the future sun and moon are all one sun and moon,” “The wonderful coming of noncoming, the true birth of nonbirth, the perfect going of nongoing, and the great death of nondeath,” and “All things in the universe have the life span of the original Buddha.”

Yoshiro Tamura, "Introduction to the Lotus Sutra", p121-122

In “Original Enlightenment and the Transformation of Medieval Japanese Buddhism,”Stone explains her understanding of Tamura’s theory:

Tamura [Yoshirō] … characterizes Tendai original enlightenment thought as “absolute affirmation of reality” and the “climax” of Buddhist philosophy, a synthesis of Tendai, Kegon, esoteric, and Zen elements that carried to the farthest possible point the denial of any separation between ordinary worldlings and the Buddha’s enlightened reality. Tamura himself terms original enlightenment thought a teaching of “absolute nonduality” (zettaifuni) or “absolute monism” (zettai ichtgen ron), a term now commonly used in Japanese scholarly writing in reference to Tendai hongaku thought. By “absolute monism,” Tamura means not a single entity or essence underlying all phenomena, but that the realm of the Buddha’s enlightenment (i.e., the realm of principle, or ri) and the conventional realm of changing phenomena (ji) are thoroughly conflated. This identification is on the one hand ontological, consistent with classic Madhyamaka teachings about the emptiness of the dharmas and the nonduality of ultimate and conventional truth, as expressed in the phrase “saṃsāra is nirvāṇa.” But in Tendai hongaku thought, the identification holds on the existential level as well: the deluded thoughts of ordinary beings as such are the Buddha’s enlightenment. In Tamura’s terms, both the “existential aspect” and “illusional aspect” of reality are “absolutely affirmed. ”

Original Enlightenment and the Transformation of Medieval Japanese Buddhism

The controversy surrounding this theory is summarized in the publisher’s description of Stone’s book:

Scholars and commentators have long recognized the historical importance of original enlightenment thought but differ heatedly over how it is to be understood. Some tout it as the pinnacle of the Buddhist philosophy of absolute non-dualism. Others claim to find in it the paradigmatic expression of a timeless Japanese spirituality. According to other readings, it represents a dangerous anti-nomianism that undermined observance of moral precepts, precipitated a decline in Buddhist scholarship, and denied the need for religious discipline. Still others denounce it as an authoritarian ideology that, by sacralizing the given order, has in effect legitimized hierarchy and discriminative social practices. Often the acceptance or rejection of original enlightenment thought is seen as the fault line along which traditional Buddhist institutions are to be differentiated from the new Buddhist movements (Zen, Pure Land, and Nichiren) that arose during Japan’s medieval period.

In Gene Reeves’ Introduction to Tamura’s book, he writes:

Some might think that the section of this book dealing with Tendai thought should be updated somehow to reflect how Tamura would have responded to recent critiques of Tendai original enlightenment thought. In fact, we can only speculate on how Tamura might have responded to such developments. My own guess is that he would have rejected any form of monistic ground, while supporting the affirmation of the reality of all things, a notion found both in the Lotus Sutra and some forms of Tendai original enlightenment thought. But, since this is simply speculation on my part, it would seem inappropriate to change Tamura’s text to reflect developments of which he was not a part.

Though Tamura does discuss Tendai thought in this book, it is really about the Lotus Sutra, and very little of what is known about the Lotus Sutra has changed since Tamura wrote it.

Yoshiro Tamura, "Introduction to the Lotus Sutra", p5