Science works, and must work, in the realm of what the Buddhist philosophers call the conceptually imputed, kun brtags. It forms hypotheses, defines quantities, builds models and tests them against observation. Even when it concludes that the universe is mental, it holds that conclusion as a concept: the concept of mind, applied to the concept of universe. Henry’s mental universe is still an object of thought. Velmans’ psychophysical ground is still a theoretical posit. This is not a weakness; it is what science is. A science that abandoned concepts would no longer be science.

The Great Perfection works in the realm of the non-imputed and the non-imputable. Rigpa is not the concept mind. Primordial purity is not the concept emptiness. The union of Samantabhadra and Samantabhadrī is not a model of reality that one believes. It is what is recognised when the activity of conceptual imputation itself is seen through, when the mind that builds models rests in its own nature and finds that it was never other than the space in which models appear. A physicist can believe that the universe is mental and still live in complete duality, grasping at self and other. A practitioner who recognises rigpa may never have heard of quantum mechanics and yet live in the very nonduality that physics only points to.

The Sanskrit word for a letter is akṣara, the imperishable. A letter does not pass away when the hand that wrote it is gone, because the sound it carries was never made by a hand. The Perfection of Wisdom sūtras open the doorway of the first letter with a single recognition. All phenomena are unborn from the beginning, and so the sound present within every other sound is the gate through which the Dharma is entered. The tantric commentaries, among them the Vimalaprabhā on the Kālacakra, read the word one step further. The imperishable is the unchanging great bliss, and the letter is the name given to its display.

The classical explanation of mantra says the same in fewer words. Mantra protects the one who reflects on it. The protection arises in the reflecting mind, and a shape on a page can only support it.

From this ground the matter of scripts takes its proper shape. Across a thousand years and half a continent, practitioners of Secret Mantra have envisioned the letters of their deities in Siddhaṃ, in Lantsa, in the Tibetan uchen, in Nāgarī and in Śāradā. The masters who reflected on these hands began, each in his own way, from what a letter is.

Anyone who walks the path of the Secret Mantra for long begins to notice a number that keeps returning. We salute Tārā twenty-one times. We recite the hundred syllables of Vajrasattva twenty-one times at the close of the day. We bless water, thread and grain with twenty-one recitations. In the Heart Essence of the Vast Expanse we meet the twenty-one semdzin, and in the cycle of the Queen of Great Bliss the twenty-one aspects of Yumka. Twenty-one lay guardians of the land were bound under oath by Guru Padmasambhava. The number seems to sit quietly at the threshold of almost every practice.

It would be easy to take it for a Tibetan habit, or for an invention of the Tārā hymn that made it famous. Yet when we follow the thread backwards, it leads not to Tibet, and not even first to the Buddha, but to the oldest voice of India: the seers of the Ṛgveda, singing of fire, rivers and the sun. The number twenty-one is a lineage in its own right. To trace it is to see how the Dharma gathered up the most ancient intuitions of the subcontinent and set them, like jewels, into the crown of the Great Perfection.

The Seventeen Tantras are the root scriptures of the Category of Pith Instructions, man ngag sde, the innermost of the three series of the Great Perfection, and therefore the summit of all nine vehicles of the Nyingma. Every teaching of the Heart Essence, from the Vima Nyingthig and the Khandro Nyingthig to the Seven Treasuries of the Omniscient Longchenpa and the Longchen Nyingthig of Rigzin Jigme Lingpa, rests on them. They are the source from which Cutting Through and Direct Crossing, the lamps, the four visions, the bardos and the rainbow body are taught.

They are called tantras, rgyud, because they reveal the unbroken continuity of the ground, the path and the fruit. Yet they differ from all other tantras. The tantras of the lower vehicles teach how to transform the impure into the pure, how to purify, accumulate and accomplish. The Seventeen teach that nothing needs to be transformed. The ground is primordially pure and spontaneously present, the path is the recognition of that ground, and the fruit is the ground recognising itself completely. What the lower tantras attain at the end of the path, these tantras introduce at the beginning.

Tsele Natsok Rangdrol, summarising the teachings of Vimalamitra, the Omniscient Longchenpa and Khenpo Ngakchung, describes them in two sentences that define the whole collection: these tantras teach in full everything a single person needs in order to practise and to reveal complete buddhahood within a single lifetime; and each of them is complete in itself, not dependent on the others. Seventeen tantras and seventeen complete paths; and yet one teaching, like a single moon reflected in seventeen waters.

Few subjects in the whole of the Buddhist path are as delicate as this one. The union of method and wisdom in the body, the path that the tantras call karmamudrā, the action seal, belongs to the most secret layer of Secret Mantra. It was never meant to be discussed in public, and the masters spoke of it, when they spoke of it at all, in symbols, in the presence of qualified disciples, and with an insistence on prerequisites so exacting that very few could ever meet them. To write about it openly is to risk two opposite harms at once.

The first harm is to profane what is profound. The completion stage of bliss and emptiness is not a curiosity, not an exotic technique, and not a licence. It is the third empowerment made into a path, the place where desire itself is recognised as the radiance of wisdom. To speak of it carelessly is to make it trivial, and to make it trivial is to close it for those who might one day be ready for it.

The second harm is to shelter what is false. In every age, and with painful clarity in our own, the language of this path has been used to clothe ordinary desire, abuse of power and the exploitation of trust in the robes of the sacred. Silence about the dangers protects no one but those who would misuse the teaching.

Between these two harms there is only one safe ground: the words of the masters themselves, read with care, in their full context, without adding anything and without taking anything away. And among all the voices of the tradition, none is more trustworthy on this subject than the Omniscient Longchenpa, who was at once the greatest systematiser of the Secret Mantra, the supreme master of the Great Perfection, and a hermit of the mountains who wrote, out of renunciation, a few verses of advice for himself and for those like him.

There is a question that every lover of the Lotus-Born carries quietly in the heart, though it is seldom spoken aloud: what would it be like to live there? Not to read about it, not to envision it for the span of a session, but to wake each morning on the Copper-Coloured Mountain, Zangdok Palri, in the presence of Guru Padmasambhava himself.

Rigdzin Jigme Lingpa answered that question in a prayer. He composed it in the Flower Cave at Samye Chimphu, the cave he called the assembly hall of all the ḍākinīs of Akaniṣṭha, at the request of a yogini of the Oral Lineage of the Vajra Queen named Dharmakīrti. He writes that the moonbeams of the compassion of the Dharma King of Orgyen and his consort fell upon his heart, and from that blessing the prayer arose. He called it The Secret Path to the Mountain of Glory.

Rigpa is neither one nor many. It is not a private possession that each being owns, and it is not a single universal substance in which all beings share. Yet the Great Perfection does not leave the matter in perfect symmetry. Because number belongs only to what can be divided and counted, and rigpa is empty in essence, every attempt to count it fails; but because its nature is luminous and self-knowing, ‘it’ is recognised in each being as that being’s own face. The tradition therefore speaks of one ground and two paths, of countless continua and a single sphere, and it leans, without ever coming to rest, towards not two rather than towards one.

Begin with the Tibetan word on its own terms, before any translation has been chosen for it. Lhun gyis grub pa breaks into lhun, a mass, a bulk, an undivided whole — the lhun of Ri rab lhun po, Meru, “the massive mountain”; the instrumental particle gyis; and grub pa, which in philosophical Tibetan does not mean “accomplished” in the sense of an achievement completed, but “established,” “existent,” “present” — the standard rendering of the Sanskrit siddha and niṣpanna. Read this way, the phrase says something closer to “established as a whole,” “present in one piece,” “complete through its own totality,” than to anything English speakers mean by spontaneous. Its weight falls on completeness and already-thereness, the way a mountain does not need to be assembled stone by stone to be a mountain. “Spontaneously accomplished,” the usual English rendering, loses this twice over: spontaneous imports a sense of sudden, uncaused arising that the Tibetan does not have, and accomplished imports an event of achievement that the Tibetan explicitly excludes. Where the word points to something that was never incomplete, the translation suggests something that has just now, suddenly, become whole.

The Seventeen Tantras are not the whole of the scriptural inheritance of the Great Perfection — they are the innermost layer of one of its three divisions, and the other two have tantric literatures of their own, in some respects older, in some respects stranger, and almost entirely unlike the Seventeen in both register and method. The common shorthand — “the Dzogchen tantras are the Seventeen Tantras of the Pith Instruction Series" — compresses two separate facts into one sentence and can leave the impression that the other two series are categories only, schools of emphasis without a textual body behind them. They are not. Each of the three series — Mind (sems sde), Space (klong sde), and Pith Instruction (man ngag sde) — has its own tantras, its own translators, its own lineage of transmission, and its own distinct way of speaking about the one Ground all three reveal.

There is an old and very exact intuition, held across every school of the Mahāyāna, that a person can be entirely free of suffering and still not be a Buddha. The arhat who has burned through craving, who meets praise and blame, gain and loss, pleasure and pain with the same unclouded evenness, who will not take another birth in saṃsāra — such a one is free. And yet the tradition insists, almost scandalously, that this freedom is not yet omniscience. Something remains. Not a torment, not a stain of the kind that makes a mind restless or cruel or afraid — something far more intimate than that, a kind of residual curvature in the very act of knowing, by which what is known still stands apart, faintly, from the knower. The entire architecture of the Mahāyāna path, and at its summit the architecture of the Great Perfection, exists to answer one question: what is this residue, and by what fire does it finally burn away?

There is the story Buddhism tells about itself, and there is the story its own texts tell when you read them in order. They are not quite the same story. The difference between them is one of the most beautiful things in the history of human thought.

It begins in a deer park near Benares, with a man taking experience apart. Body, feeling, perception, formations, consciousness: five heaps, and in none of them anything that deserves to be called a self. It ends, many centuries later, in the high valleys of Tibet, with yogins sitting under an open sky who recognise that what knows was never born, never stained, never for one moment absent. The first teaching asks: what binds us? The last asks: what are we when nothing binds us?

This essay walks the road between those two questions, through the primary sources themselves. It will not pretend that the later teachings were hidden in the earlier ones, waiting to be unwrapped. Nor will it accuse the later masters of betrayal. It wants to see exactly where the ground moved, and to sit, without flinching, in the places where the tension still hums.

When a Dzogchen practitioner closes a session with the wish that all beings reach the highest state, she is speaking, without knowing it, in the words of a hymn sung to Viṣṇu more than three thousand years ago. The same is true of the Theravāda monk who chants of the deathless state, of the Śaiva yogin who rests in the supreme plane of consciousness, and of the Advaita-Vedāntin who seeks the place from which there is no return. All of them use one small word, pada: the step, the footprint, the place where the foot comes to rest.

samarasapadalīno niḥsvabhāvaikavīraḥ
śamitasakalabhāvairjñānadṛṣṭiprakāśaḥ |
viditaparamatattvo labdhavijñānasaukhyo
nayitaparamabodho jñānanetrādyanāthaḥ ||

“Merged in the state of the same taste,
the Solitary Hero free from intrinsic nature;
the radiance of the vision of awareness,
all states of being stilled;
he who has known ultimate reality
and found the bliss of realisation,
and who has led others to the supreme awakening:
Jñānanetra, the first Lord.”

- Hymn to the Five Wheels of Space, Verse 3

Although this verse sounds like a praise from the Atiyoga tradition of Tibet, it is not. It is a praise from the Atinaya tradition of Kashmir. It is about Jñānanetra, its mysterious founder who attained empowerment in Oḍḍiyāna and, upon his return from Oḍḍiyāna, founded Kashmir’s first nondual system: the Krama (the Sequential), also called Mahānaya (the Great Path), Mahāmnāya (the Great Transmission) or Atinaya: the Path of Ati.

Two words carry the entire weight of what the Great Perfection says about the mind, and they are almost always rendered by the same English word. Ye shes (ཡེ་ཤེས་) and rig pa (རིག་པ་) are both translated as “awareness”, “wisdom”, “pristine cognition”, “gnosis”, “intrinsic awareness”. A student is told to rest in rigpa, that yeshe is spontaneously present, that the five wisdoms are the nature of the five poisons, that awareness knows itself (rang rig, རང་རིག་). The student quite reasonably concludes that the Dzogchen tradition has one thing to say and says it in several ways.

That conclusion is half right, and the half that is wrong is instructive. The two words have different histories. Ye shes renders jñāna, the Buddha’s wisdom, which the Mahāyāna and the tantras placed first at the end of the path and then, with growing boldness, at its beginning and in its ground. Rig pa renders vidyā, knowledge as the opposite of ignorance (avidyā), the pole on which the Buddha’s own awakening was first described. These two inheritances were joined in the Great Perfection by a third idea that Indian Buddhist philosophers fought over for a thousand years: svasaṃvedana, the self-knowing of knowing itself. They fought over it because it appears to ask for the impossible, an awareness that is neither an object for another awareness nor in need of one.

The Great Perfection’s wager is that this impossible thing is not a theoretical postulate but the ordinary condition of the ground, which can be pointed out and recognised. This essay follows four words — jñāna, vidyā, svasaṃvedana and svasaṃvedya (what can be known only by itself) — through their Indian history, and then asks what the Great Perfection does with them.

A practitioner who practises a Dzogchen teaching will hear four expressions used as though they named one reality and, a moment later, as though they named four. In the morning, a ngöndro text invites the practitioner to rest in the dharmadhātu (ཆོས་དབྱིངས་, chos dbyings). At midday, another sādhana text calls it the dharmakāya (ཆོས་སྐུ་, chos sku). In the completion stage practices of the early evening, it might become the vast expanse (ཀློང་ཆེན་, klong chen), and at night, when the practice turns to the visions, the expanse of space (ནམ་མཁའི་དབྱིངས་, nam mkha’i dbyings). Translators have offered “basic space”, “reality body”, “great expanse”, and “space”, sometimes using the last for all four. The student is left to suspect either that the tradition is lavishly redundant or that some distinction is being withheld, or that the translators are simply confused.

None of these suspicions is correct. The four terms are not four things, and they are not four synonyms. They are four disclosures of one ground, each answering a different question that may be put to it. The dharmadhātu answers where and whence: the realm in which, and the source from which, everything that appears arises. The dharmakāya answers who and how present: the way the same ground is present as awakened being. The vast expanse answers how far and how free: the limitlessness in which neither centre nor edge can be found. The expanse of space answers like what: the ground under the example of space, and, in the visionary practice, the very sky upon which its radiance appears.

The Song of the Vajra from the Tantra of the Union of the Sun and Moon was never composed. It was not written by a poet, not translated from one language into another, not invented to please gods or men. It is the natural sound of Samantabhadra in union with Samantabhadrī, the self-resounding of the dharmakāya in the space of its own wisdom. The tantras call it dorjé lu, the Song of the Vajra. Its syllables are not Sanskrit and not Tibetan; they are the symbolic speech of the ḍākinīs of Oḍḍiyāna, a language that does not describe reality but is reality sounding itself.

This essay makes one claim and makes it without hesitation. The Song of the Vajra is everything. It is refuge. It is bodhicitta. It is Semdzin, the holding of the mind. It is Tsa Lung, the yoga of channels and winds. It is Rushen, the separation of saṃsāra and nirvāṇa. It is Trekchö, cutting through to primordial purity. It is Direct Crossing, the spontaneous presence of the four visions. And at its end it is even the dedication of merit. One who sings it while resting in the nature of mind has, in that very singing, accomplished the entire path, from the first refuge to the fruition of the three kāyas.

There is a story about the Buddha that has been told so often it has hardened into a kind of certainty: that he rose up against the Vedic world, overturned the authority of the brahmins, abolished caste, and founded a religion that stood from its first day in opposition to everything that would later be called Hinduism. It is a stirring story, and it flatters modern sensibilities. It is also, in its simple form, not what the oldest texts say.

When we open the Pali Canon itself and read it slowly, a different and far more interesting picture emerges. The Buddha speaks of the ancient seers with reverence. He addresses brahmins as friends, debates them as equals, accepts them in great numbers into his community, and redefines their highest title rather than discarding it. He criticises animal sacrifice and the pride of birth, as the Upaniṣads and the Bhagavad Gītā also do. His sharpest words are reserved not for the Vedic heritage as such but for its corruption, for a priesthood that has forgotten what its own forefathers knew.

This is not to deny that something new and radical entered the world with the Buddha. It did. Nor is it to deny that the relationship between Buddhists and brahmins later knew real hostility, rivalry for royal favour, and bitter polemic. It did. But between the simple story of opposition and the equally simple story of sameness lies the truth: two great streams of Indian contemplative life, born from the same ground, drawing on the same language, the same seers, the same longing for liberation, and illuminating one another, again and again, for two and a half thousand years.

What follows traces that relationship from the oldest suttas to the Great Perfection, and from the forest debates of the Buddha's own time to the meeting of Yogācāra and Advaita, of Śaiva and Buddhist tantra, and perhaps of the Bhagavad Gītā and the teaching of buddha-nature itself.

There is a word in the Great Perfection that opens like a window in a dark room. It is spoken in the tantras of the Heart Essence, explained by the Omniscient Longchenpa in his treasuries, sung by Rigzin Jigme Lingpa, whispered by Patrul Rinpoche to his students under open skies, and it is the word with which a dying yogi is told, in the moment that decides everything, not to be afraid. The word is rangdang, natural radiance.

Awareness is clear; its clarity shines; that shining is its natural radiance. Yet in this one word the whole of the Great Perfection is folded: the nature of the ground before anything has appeared, the origin of saṃsāra and nirvāṇa, the secret of the body's channels and lamps, the essence of both Cutting Through and Direct Crossing, the meaning of the lights at death, and the fruition in which the body itself returns to light.

Natural radiance is not a light that someone kindled. It was never lit, and so it can never go out. It does not shine on things from outside, as the sun shines on a mountain. It shines as things, from within, as a jewel shines with its own lustre. Every appearance that has ever arisen, every thought that has ever moved, every vision of every yogi, every sorrow and every delight, has been nothing other than the natural radiance of awareness, mistaken or recognised.

Few images in the literature of the Great Perfection (rdzogs pa chen po) are as central, or as loaded, as the youthful vase body (gzhon nu bum pa’i sku; abbreviated gzhon nu bum sku). In the Seventeen Tantras of the Seminal Heart (snying thig) and in the Omniscient Longchenpa’s (1308–1364) systematisation of them, the expression names the primordial ground (gzhi) in its state of inward luminosity (nang gsal), prior to the ground’s manifestation (gzhi snang). It thus stands at the hinge of the tradition’s (non-imputed, non-reified) cosmogony, its soteriology and its contemplative physiology. The same image that describes the condition “before” saṃsāra and nirvāṇa also names the fruition into which the visionary path finally resolves.

This essay asks two questions. The first is exegetical: what exactly does the expression mean in the tantras and their principal commentators? The second is genealogical: do earlier Indian and Tibetan sources supply the elements from which the image was composed, namely the sealed vessel, the luminous presence within it, its youthfulness, and its bursting open?

In the sky-like expanse where nothing has ever been born, the sound of the Dharma arises by itself. Out of that soundless sound came a short song of Nyala Pema Düdul, a few lines only, spoken to a circle of disciples who had asked for it again and again.

In it he names the eight worldly concerns: gain and loss, pleasure and pain, fame and obscurity, praise and blame. He declares that whoever still clings to the good and recoils from the bad cannot even be called a practitioner of non-dual self-liberation. And then, in a single breath, he opens the entire path: all that arises, delightful or painful, is like the ten similes of illusion. Recognise this, and rest in the expanse of the view, beyond the ordinary mind, beyond words, thought and description, beyond the borders of hope and fear.

He signed it as the old beggar Padma. In 1872 that old beggar dissolved into the body of light, leaving only hair and nails, as the elements of his form returned to their luminous source. From his realisation the stream flowed to Adzom Drukpa, and from Adzom Drukpa it flows on into our lineage. When such a one speaks of the eight concerns, it is not a moralist speaking. It is the voice of the ground itself, in which not a trace of them remains.