There is a view that sees nirvana as the termination of excessive influence by trsna (Skt) or tanha (Pāli), literally meaning “thirst” but usually suggestive of “desire” or “craving.” There is nothing wrong with being thirsty; it’s the value we put on it that becomes the problem. Obsessive desire is descried as a fever in the Buddhist literature. Cessation of passion is described the cooling after a fever. It’s expressed as the renewal of heath. In the Buddha’s time the related adjective nubbuta was a commonly used word meant to illustrate one who is again well after suffering an illness. This would indicate that the original Buddhist goal, nirvana, was the renewal of healthy conditions of life here and now: not in a remote and transcendent realm beyond this very life.

This is why in Mahayana Buddhism maintain that samsāra, the world of suffering and nirvana are not exclusive but interpenetrating. When one is afflicted by disease or suffering from the fever of harmful craving then this is said to be the world of samsāra. Conversely, when one is healthy and free of fever, the world appears differently; more positive, nourishing, and this is a nirvana experience. In this respect it is nirvana is not so much the lack of suffering, but the transcendence of suffering instead.

Buddhas do not acquire some exclusive realization that the rest of us do not have. They have changed the way they discern the world. This is why when the Buddha just after his “enlightenment” was asked by a wanderer who or what he was, he simply said, “Buddho”, I understand.

The potential for disease is always present. Recovery from a fever does not prevent its return. The potential for illness is always present along with the potential for health. Health may be said to be the realization that the potential for nirvana coexists with the potential for samsāra. There not two separate worlds, one full of suffering and one full of serenity. This is the dissolution of dualistic thinking.

An ordinary person and a Buddha are not two different classes of persons, even though they might be two different modes of “being.” The potential for enlightenment is present; an ordinary person can realize enlightenment and become a Buddha. One strategy to oppose our tendency toward dualistic thinking is to say that we are already Buddha, albeit an unrealized one. This is only a tactic.

The Chinese T’ien-T’ai master Zhiyi taught a doctrine called “the Ten Realms” or more exactly, “The Ten Life-conditions and their Mutual Possession.” The Ten Life-conditions, or spiritual realms (Jpn jikkai), are potential mental states inherent in each living being. In ascending order he called them the Hell, Hunger, Animalistic, Anger, Humanity, Rapture, Learning, Realization, Bodhisattva and Buddhahood realms. In the Moho Chih Kuan (“Great Stopping and Seeing”) Zhiyi wrote,

One mind contains ten spiritual realms. At the same time, each of the ten spiritual realms contains all the others; giving a hundred spiritual realms … It is obscure, subtle, and profound in the extreme. Knowledge cannot know it, nor can words speak it. Herein lies the reason for its being called ‘the realm of the inconceivable.

The numbers are another way to articulate the non-dualism of nirvana and samsāra. Hell contains Buddhahood and Buddhahood contains hell and the rest of the worlds as well. The realms are potential conditions that can be experienced at any given moment.

The potential for Buddhahood should not be disparaged. This is not to say that we can simply think we are a Buddha and make it so. Realization enlightenment is a process. We have to tear away at our karma, dualistic mind, our prejudices and attachments. It can be painful.

T’ien T’ai Buddhism stresses the importance of starting with this basic understanding of “original enlightenment” (Jpn Hongaku), natural Buddha-nature, the commonality of all life-conditions. Awareness that this potential to be a Buddha exists is the first step in uncovering it our Buddhahood.

Tsungmi, the fifth and final patriarch of the Huayan, Flower Garland School, and a Ch’an (Zen) Master of the Hotse School, explained,

All sentient beings have been endowed with the true mind of original enlightenment. From the beginningless beginning this mind has been constant, Pure, luminous, and unobscured; it has always been characterized by bright cognition; it is called the Buddha Nature or the Womb of the Awakened.

From the beginningless beginning the delusions of human beings has obscured it so that they have not been aware of it. Because they recognize in themselves only the ordinary person’s characteristics, they indulge in lives of attachment, increasing the bond of karmic power and receiving the sufferings of birth and death. Out of compassion for them, The Awakened One taught that everything is empty; then he revealed to all that the true mind of spiritual enlightenment is pure and is identical with that of the Buddhas.

In Jacqueline I. Stone’s Original Enlightenment and the Transformation of Medieval Japanese Buddhism (Kuroda, 1999), it is written,

The Buddhas who appear in sutras, radiating light and endowed with excellent marks, are merely provisional signs.  The “real” Buddha is the ordinary worldling.  Indeed, the whole phenomenal world is the primordially enlightened Tathāgata [Thus-Gone One]. Seen in their true light, all forms of daily conduct, even one’s delusive thoughts are, without transformation, the expressions of original enlightenment. Liberation is remained, not as the eradication of mental defilements or as achieving birth in a pure land after death, but as the insight, or even the faith, that one has been enlightened from the very beginning.

Stone later writes, “Hongaku (original enlightenment) thought is best understood not as a tightly organized philosophical system that rejected inconsistent elements, but as a broad perspective from which the entirety of the received [Buddhist] tradition could potentially be reinterpreted in immanentalist terms.” She notes that this “perspective” traditionally did not reject or dismiss various forms of Buddhist practice but saw the practices from a different perspective.

Original enlightenment is fundamentally the creation of Japanese Tendai Buddhism, the school based on the Chinese T’ien-T’ai sect. In T’ien-T’ai, original enlightenment is inferred by the teaching of the innate potential for awakening as a possession of all living beings, Buddha-nature. Japanese Tendai elevates hongaku to the status of the original nature of all phenomena.

The idea of original enlightenment comes from numerous and varied sources. Nāgārjuna, the starting point for almost everything Mahayana, is one of them. It was T’ien-T’ai master Zhiyi who was perhaps the first to emphasize the harmony and unity within Nāgārjuna’s teachings. The idea that there was one essence or one nature of all things both stained and pure is expressed in Nāgārjuna’s conception of the dharma-dhatu or dharma-realm.

Dharmadhatu refers to the ultimate reality, Nirvana, the ultimate nature of all that is conditioned and contingent. Dharma symbolizes Nirvana while Dhatu suggests the sense of the essential, intrinsic, inmost nature, the fundamental, ultimate essence. It is the principal undertaking of the spiritual nomad to realize the dharmadhatu.”

Nāgārjuna puts it, “Even as it is the very nature of water to flow down by reason of which all waters return to the great ocean, blend and become of one essence, just in the same way all determinate entities, all natures general and particular, return ultimately to dharma-dhatu, blend and become of one essence with it. This is dharma-dhatu. Even as the diamond which is at the top of the mountain gradually settles down until it reaches its destination, the field of diamonds, and having got there it will have got back to its self-nature and only then does it come to a stop, this is the case with all things. Through knowledge, through discrimination, (the mind seeks the true nature of things and thus) gets to tathāta [thusness]. From tathāta, the mind enters its original nature, where it remains as it ever was, devoid of birth (and death) and with all imaginative constructions put an end to. This is the meaning of dharma-dhatu.”

This one essence is all-essence or all the natures of all things. It is the totality of phenomena experience. It is called “one” to underscore the interdependency of all things. Tendai calls it “the mutual possession of all natures.” Dharma-dhatu is not a realm exterior of our lives. “To flow into the ocean of dharma-dhatu” is only a metaphor and not to be taken literally. It is a symbol for Nirvana here meaning “ultimate” reality, but since it is separate from this samsāric world of suffering it cannot be said to be “ultimate” at all — it is our reality.

The teaching of Buddha-nature (Buddhasvabhava) developed from The Awakening of Faith. The theory of the tathāgatagarbha (realm of the Thus-Gone) is based on the Nirvana Sutra. Both greatly influenced T’ien-T’ai/Tendai thinking because of the correlation of the Nirvana Sutra to the Saddharmapundrarika (“Lotus Sūtra”).

One early Chinese Buddhist scholar, Taosheng, taught that Yogācāra classification of icchantika, beings too defiled and deluded to realize awakening, could indeed realize Buddhahood. Taosheng could not admit to the existence of the icchantika because the Lotus Sutra is clear that all beings without exception have the Buddha-nature.

Obviously delusional people exist, but they do not exist as a separate and distinct category of beings. Because delusion is universally latent tendency all people participate in delusion. If delusions were not existent there would be no need to practice and transcend them. The Buddha’s teaching or practice would be irrelevant and attaining Buddhahood merely a cool kind of mythology. It’s easy to see how this influenced Zhiyi in his teachings concerning the nature of evil. The sense of dualism is the king of all delusions. Good and evil, pure and impure, deluded and Buddha do not exist from their own sides, independent of anything else. All conditions of life co-exist with one another, penetrate and are possessed by all.

Tendai’s primary influence was the Lotus Sutra and holds this sutra in the utmost as the teaching of Buddha. It seems to infer the inherency of Buddha-nature providing a doctrinal foundation for idea of original enlightenment. This verse is from the Lotus Sutra,

Among those who have heard the Dharma,
None will fail to become Buddha.
All Buddhas have taken the vow:
‘The Buddha-way which I walk,
I desire to enable all livings beings
To attain the same way with me.’

Buddhas are symbols, provisional signs, which from beginningless time have appeared in the world, to bring enlightenment within the reach of all beings. Acting as guides, they point to the potential within each of that only each individual can initiate. The Buddha may be said to empower us, but that power does not originate from the Buddha. It is our own. We can use it; nurture it, because it is the same nature as Buddha.

The importance of hongaku shiso or original enlightenment thought is that it opens all Dharma gates to all people. It universalizes the enlightenment process to include every living being. It is not a privilege to enter into enlightenment for the spiritually gifted nor is it something to be attained only by the consummate practitioner or vastly learned. Buddhahood is attainable to all because the seed of enlightenment, Buddha-nature, is indiscriminate and universal.

Dogen, the founder of Soto Zen, wondered if we are originally enlightened, why is it necessary to practice. Tsungmi beat Dogen to the punch by already explaining that it is because from the beginningless beginning the delusions of human beings has obscured it so that they have not been aware of it.

We have a tendency to approach enlightenment as something mystical. Enlightenment is not so very different from anything else we do. If a person is talented in art the talent is said to be present. That talent must be developed and skillfully used before it can ripen. Like any other talent, Buddha-nature too has to be awakened. Becoming a Buddha takes practice. Meditation is a Buddhists tool to use in developing Buddha-nature. Practice is essential. Dogen referred to it as “oneness of practice and enlightenment.” It’s pretty simple.

If only a Buddha can attain Buddhahood then what is the point of practice? Buddhism would simply be one more ism in a world of isms.

We utilize original enlightenment every time we see deeper into ourselves and become more aware of what’s happening around us, within us. Buddha-nature arises when wisdom grows, when more skilful decisions are made temptations resisted, and when the Buddha-nature in others is seen.

As Zhiyi taught, the world of Buddhahood contains the world of Hell. Imperfect as anyone of us can be, just where we are — we are Buddha. That potential is always present. It would be a waste of time to look anywhere else.

Buddha-Nature exists in everyone no matter how deeply it may be covered over by greed, anger and foolishness, or buried by his own deeds and retribution. Buddha-Nature cannot be lost or destroyed; and when all defilements are removed, sooner or later it will reappear.

The Dalai Lama