TL;DR: The Diamond Sutra and the Heart Sutra both belong to the Prajnaparamita system, teaching that all dharmas lack a fixed self-nature and that practitioners should not cling to forms or to words. Zen values these two sutras because they match its principle of "not relying on written words, transmitting the mind with the mind", though the way they are read and the emphasis placed on them differ between Zen lineages. These are texts of the Chinese canon, transmitted to Vietnam over many centuries, not compositions of Vietnamese Buddhism.
What Are the Diamond Sutra and the Heart Sutra?
The Diamond Sutra and the Heart Sutra are two short sutras belonging to the Prajnaparamita system, the group of Mahayana texts discussing the wisdom that sees the emptiness of all phenomena. The Diamond Prajnaparamita Sutra was translated into Chinese by Kumarajiva during the Later Qin dynasty[3], while the Prajnaparamita Heart Sutra was translated by Xuanzang during the Tang dynasty[1]. Both are part of the Chinese Buddhist canon, transmitted to Vietnam along the Northern Buddhist stream over many centuries, not texts composed by Vietnamese Buddhism[1].
The name "Diamond" refers to the diamond gem, meaning the Prajnaparamita wisdom is sharp enough to cut through all delusive clinging. "Heart Sutra" means the sutra that condenses the essential core, only about two hundred Chinese characters yet encompassing the entire teaching of emptiness and the Bodhisattva path.
Why Does Chan Buddhism Particularly Value These Two Sutras?
Chan Buddhism values the Diamond Sutra and the Heart Sutra because these two texts do not build a complex doctrinal system, but directly break clinging to concepts, forms, and words. This aligns with Chan's principle of "not establishing words and letters, transmitting the mind through the mind." In Buddhist philosophy, Phan Van Hum (1942) notes that Chan Buddhism, transmitted by Bodhidharma, advocates not establishing words and letters, so it does not discuss the world or human life, focusing only on liberation. He also emphasises that using words to explain true reality easily falls into the realm of phenomena, failing to reach true reality[2].
However, one must distinguish between "not establishing words and letters" and "rejecting scriptures." Zongmi writes in the Chan Yuan Zhu Quan Ji Du Xu that unless one matches the provisional and real sutras and treatises to the deeper and shallower Chan schools, one cannot use the teachings to illuminate the mind and the mind to explain the teachings[5]. This means scriptures are still used as a means of illumination, only they must not be turned into an end in themselves.
What Does the Diamond Sutra Teach About Bodhisattvas and Non-Clinging?
The opening of the Diamond Sutra is a very ordinary scene: at the Jetavana Grove in Sravasti, the Buddha with twelve hundred and fifty bhikshus in the assembly; when the almsround time came, he put on his robe, took his bowl, and went into the city for alms, then returned to eat, put away his robe and bowl, washed his feet, spread his seat, and sat down[3]. This detail matters because it shows that emptiness in the Diamond Sutra is not outside daily life, but is spoken right from eating, wearing, walking, and standing.
The core of the sutra discusses the Bodhisattva liberating beings without seeing any being liberated. If a practitioner still holds the notion "I am a Bodhisattva," "I am saving people," then they have fallen into clinging to self and clinging to phenomena. The sutra repeatedly compares the merit of giving the seven treasures with the merit of upholding this sutra, even just four lines of its verse, and says the latter is greater[3]. A key line of the sutra is "one should give rise to the mind without abiding anywhere" (應無所住而生其心, ying wu suo zhu er sheng qi xin)[3].
What Does the Heart Sutra Say in Just Over Two Hundred Characters?
The Heart Sutra opens with the story of Bodhisattva Avalokiteshvara, while practising deeply the Prajnaparamita, saw that the five aggregates are all empty, and overcame all suffering[1]. This is the foundational statement: suffering is not eliminated by avoiding suffering, but by clearly seeing the emptiness of the five aggregates.
After that, the sutra tells Shariputra that the emptiness of all phenomena is neither arising nor ceasing, neither defiled nor pure, neither increasing nor decreasing[1]. The sutra then sets out a series of negations: in emptiness there is no form, feeling, perception, mental formation, or consciousness; no eye, ear, nose, tongue, body, or mind; no form, sound, smell, taste, touch, or objects of mind; no realm of eye-consciousness up to no realm of mind-consciousness; no ignorance, and no extinction of ignorance; up to no aging and death, and no extinction of aging and death; no Suffering, Accumulation, Cessation, Path; no wisdom and no attainment[1].
The point to note is that the Heart Sutra negates both the Four Noble Truths and the entire path of practice, not just suffering. This is easily misunderstood as nihilism. In fact, according to the sutra's next words: because there is nothing to attain, Bodhisattvas rely on Prajnaparamita and their minds are without hindrance; because there is no hindrance, there is no fear, and they escape delusive afflictions, attaining ultimate Nirvana[1]. That is, negation does not lead to nihilism, but to liberation.
The sutra ends by praising Prajnaparamita as the great divine mantra, the great illuminating mantra, the supreme mantra, the unequalled mantra, capable of removing all suffering, true and not false, then recites the mantra: "Gate, gate, paragate, parasamgate, bodhi svaha"[1]. Trần Trọng Kim (1958) gives Xuanzang's version in Appendix II, with a Sino-Vietnamese transliteration and a Vietnamese meaning translation, and notes that the sutra has seven translations of which Xuanzang's is the most widely used[1].
The Role of the Diamond Sutra in the Platform Sutra and the Chan Tradition
According to the Platform Sutra of the Sixth Patriarch, Huineng recounted that when he was still gathering firewood: one day carrying firewood to market, he heard a customer reciting the Diamond Sutra, was astonished, asked what this teaching was and from whom he received it; the customer replied that this Diamond Sutra was received from Master Hongren at Huangmei, so Huineng asked his mother's permission and set out to find the teacher[4]. The line he heard, according to the Platform Sutra text on Wikisource, was "one should give rise to the mind without attachment" (應無所著而生其心), while Kumarajiva's Diamond Sutra reads 應無所住而生其心[3]. This is one of the historical reasons the Diamond Sutra is closely tied to Chan Buddhism: it was the direct cause leading to the Sixth Patriarch's turning point.
Also in the Platform Sutra, Huineng taught that all Prajna wisdom arises from self-nature, not from outside; he explained that Prajna means wisdom, and Paramita means reaching the other shore, that is, leaving birth and death. According to him, whoever wishes to enter deeply into Prajna samadhi must practise the Prajna conduct, and reciting and upholding the Diamond Prajnaparamita Sutra will surely lead to seeing one's nature; he also affirmed that the merit of this sutra is immeasurable and boundless[4]. This is the most direct place showing that Chan Buddhism does not at all neglect the Diamond Sutra, despite its principle of not establishing words and letters.
Do Different Chan Lineages Emphasise Them Equally?
Not entirely. Zongmi's Chan Yuan Zhu Quan Ji Du Xu records that the Chan schools of his day set up their teachings and transmissions in ways that contradict one another[5]: some lineages take "emptiness" as the root, some take "knowing" as the source, some say only silence is true, some say both practice and sitting are necessary. Therefore, when saying "Chan Buddhism values the Diamond Sutra," one should understand this as a general tendency, not a uniform rule for all branches.
| Criterion | Diamond Sutra | Heart Sutra |
|---|---|---|
| Chinese translator | Kumarajiva, Later Qin dynasty | Xuanzang, Tang dynasty |
| Length | Longer, about five thousand Chinese characters | Short, about two hundred Chinese characters |
| Structure | Dialogue between the Buddha and Subhuti | Dialogue between Avalokiteshvara and Shariputra |
| Focus | Bodhisattva liberating beings without clinging to marks | Emptiness of the five aggregates and all phenomena |
| Role in Chan | Foundational sutra of the Sixth Patriarch, recommended for recitation | Daily recitation sutra, widely popular |
Why Are These Two Sutras Easily Misunderstood?
Both sutras use strongly negative language, so they are easily read as nihilism or as a statement that Buddhism denies morality. The Heart Sutra negates even Suffering, Accumulation, Cessation, Path[1], but immediately after says Bodhisattvas rely on Prajna and their minds are without hindrance, without fear, attaining ultimate Nirvana[1]. That is, the negation here breaks clinging to concepts, not destroys moral life.
Another misunderstanding is thinking "not establishing words and letters" means not needing to read sutras. Phan Van Hum (1942) notes that Chan Buddhism advocates "not establishing words and letters," has no discussion of the world and human life, focusing only on liberation. But the Platform Sutra itself teaches reciting the Diamond Sutra to see one's nature, and the Chan Yuan Zhu Quan Ji Du Xu says one needs to use teachings to illuminate the mind. These two are not contradictory if "not establishing words and letters" is understood as not clinging to words, not as not using words.
Influence in Vietnam
Buddhism entered our country very early. In Buddhist philosophy, Phan Van Hum (1942) observes that Vietnamese people have long been imbued with Buddhism, to the extent that many who do not go to pagodas, do not worship the Buddha, and have no clear awareness of Buddhism still carry Buddhist thought, whether Theravada or Mahayana. He also cites Tran Van Giap's survey of Buddhism in Annam from its first transmission to the thirteenth century, published in the Bulletin de l'École française d'Extrême-Orient in 1932.
In that context, the Diamond Sutra and the Heart Sutra are widely recited in Vietnamese Northern Buddhist pagodas. However, note that these are Chinese canon texts transmitted through Chinese mediation, not original texts of Vietnamese Buddhism[1]. This distinction matters so as not to attribute to Vietnamese Buddhism what belongs to the East Asian tradition.
Conclusion
The Diamond Sutra and the Heart Sutra are not competing texts but complement each other: the Diamond Sutra is long, going deep into Bodhisattva conduct and non-clinging to marks; the Heart Sutra is short, condensing the teaching of emptiness and the Prajna path. Chan Buddhism values both because they do not build a conceptual system to cling to, but directly break clinging. However, the degree of emphasis and manner of reading differ among Chan lineages, and "not establishing words and letters" versus "using words as a means" are two things to distinguish clearly.
