According to Alex Wayman, the idea of the tathāgatagarbha is grounded on sayings by the Buddha that there is something called the luminous mind (prabhasvaracitta), "which is only adventitiously covered over by defilements (agantuka klesha).
[11] According to Wayman, the teachings of the Avataṃsaka Sūtra (1st–3rd century CE), which say that the Buddha's knowledge is all pervasive and is present in all sentient beings were also an important step in the development of buddha-nature thought.
[19] The Lotus Sutra, written between 100 BCE and 200 CE, also does not use the term tathāgatagarbha, but Japanese scholars suggest that a similar idea is nevertheless expressed or implied in the text.
[48][49][50][51][52] The Tathāgatagarbha Sūtra uses nine similes to illustrate the concept:[53] This [tathāgatagarbha] abides within the shroud of the afflictions, as should be understood through [the following nine] examples: Just like a buddha in a decaying lotus, honey amidst bees, a grain in its husk, gold in filth, a treasure underground, a shoot and so on sprouting from a little fruit, a statue of the Victorious One in a tattered rag, a ruler of humankind in a destitute woman's womb, and a precious image under clay, this [buddha] element abides within all sentient beings, obscured by the defilement of the adventitious poisons.Another important and early source for buddha-nature is the Mahāyāna Mahāparinirvāṇa Sūtra (often just called the Nirvana Sutra), possibly dating to the 2nd century CE.
[15] The Mahāparinirvāṇa Sūtra linked the concept of tathāgatagarbha with the "buddhadhātu" ("buddha-nature" or "buddha-element") and it also equates these with the eternal and pure Buddha-body, the Dharmakaya, also called vajrakaya.
[56][57][57] The Nirvana sutra further claims that buddha-nature (and the Buddha's body, his Dharmakaya) is characterized by four perfections (pāramitās) or qualities: permanence (nitya), bliss (sukha), self (ātman), and purity (śuddha).
Bhaviveka's Tarkajvala states: [The expression] "possessing the tathagata heart" is [used] because emptiness, signlessness, wishlessness, and so on, exist in the mind streams of all sentient beings.
[95][99] This text was in line with an essay by Emperor Wu of the Liang dynasty (reign 502–549 CE), in which he postulated a pure essence, the enlightened mind, trapped in darkness, which is ignorance.
[109] Jizang was also one of the first Chinese philosophers to famously argue that plants and insentient objects have buddha-nature, which he also termed true reality and universal principle (dao).
The Huayan tradition heavily relied on buddha nature sources like the Awakening of Faith and on the doctrine of principle (理, li, or the ultimate pattern) and phenomena (shi).
Suzuki, the Zen view of buddha-nature can be found in the Laṅkāvatāra Sūtra, which states that one must let go of all discriminating notions of any kind to attain the perfect knowledge of the tathāgatagarbha.
[126] According to Heng-Ching Shih, the teaching of the universal buddha-nature does not intend to assert the existence of substantial, entity-like self endowed with excellent features of a Buddha.
[5] Hsing Yun, forty-eighth patriarch of the Linji school, equates the buddha-nature with the dharmakāya in line with pronouncements in key tathāgatagarbha sūtras.
[129] Jacqueline Stone writes that Tendai doctrine held that enlightenment was "inherent from the outset and as accessible in the present, rather than as the fruit of a long process of cultivation.
The founder of the Jōdo Shinshū of Pure Land Buddhism, Shinran, equated buddha-nature with the central Shin concept of shinjin (true faith or the entrusting mind).
[131] The founder of the Sōtō school of Zen Buddhism, Dōgen Zenji, held that buddha-nature was simply the true nature of reality and being.
[133][134] The emphasis in Nichiren Buddhism is on attaining Buddhahood in this lifetime, described as manifesting or summoning forth buddha-nature by chanting the name of the Lotus Sutra: Namu Myōhō Renge Kyō[135][136] Like the classic Tendai hongaku doctrine, Nichiren held that all life and even all insentient matter (such mandalas, images, statues) also possesses buddha nature, because they serve as objects of worship.
[144] The teaching of buddha-nature is also a key source for Tibetan Dzogchen texts, which presents the sugatagarbha as equivalent to the ultimate ground or basis of all reality.
This teaching can be found in early Dzogchen sources like Nubchen Sangye Yeshe's (9th century) Lamp for the Eye of Contemplation equates buddha-nature with this ultimate basis, which it also calls by various names like "the spontaneous essence", "the innermost treasury of all vehicles", "the great universal grandfather [spyi myes], is to be experienced directly by self-awareness [rang rig pas]", "sphere of the great circle [thig le chen po'i klong] of the self-awareness.
[149] Mipham Rinpoche, the most authoritative figure in modern Nyingma, adopted a view of buddha-nature as the unity of appearance and emptiness, relating it to the descriptions of the ground in Dzogchen as outlined by Longchenpa.
[156] The modern Nyingma scholars Khenchen Palden Sherab (1938–2010) and Khenpo Tsewang Dongyal (born 1950), emphasise that the essential nature of the mind (the buddha-nature) is not a blankness, but is characterized by wonderful qualities and a non-conceptual perfection that is already present and complete, it's just obscured and we fail to recognize it.
[162] According to Brunnholzl, Dolpopa, basing himself on certain tathāgatagarbha sutras, argued that the buddha-nature is "ultimately really established, everlasting, eternal, permanent, immutable (therzug), and being beyond dependent origination.
The Buddhist tantric scripture entitled Chanting the Names of Mañjuśrī (Mañjuśrī-nāma-saṅgīti), repeatedly exalts, as portrayed by Dolpopa, not the non-Self but the Self, and applies the following terms to this ultimate reality: "the Buddha-Self, the beginningless Self, the solid Self, the diamond Self."
[163] Cyrus Stearns writes that Dolpopa's attitude to the third turning of the wheel (i.e. the buddha-nature teachings) is that they "are the final definitive statements on the nature of ultimate reality, the primordial ground or substratum beyond the chain of dependent origination, and which is only empty of other, relative phenomena.
"[164] According to Brunnholzl, "virtually all Kagyu masters hold the teaching on buddha nature to be of definitive meaning and deny that the tathagata heart is just sheer emptiness or a nonimplicative negation.
Shenpen Hookham, Oxford Buddhist scholar and Tibetan lama of the Shentong tradition writes of the buddha-nature or "true self" as something real and permanent, and already present within the being as uncompounded enlightenment.
[170] Buddhist scholar and chronicler, Merv Fowler, writes that "the main message of the tathagatagarbha literature" is that buddha-nature really is present as "a hidden essence" within each being.
According to Matsumoto Shirõ and Hakamaya Noriaki of Komazawa University, essentialist conceptions of buddha-nature are at odds with the fundamental Buddhist doctrine of dependent origination and non-self (anātman).
[6][175] Likewise, Hirakawa Akira, sees buddha-nature as the potential to attain Buddhahood which is not static but ever changing and argues that "dhātu" does not necessarily mean substratum (he points to some Agamas which identify dhatu with pratitya-samutpada).
Lusthaus notes that the Huayen thinker Fa-tsang was influential in this theological trend who promoted the idea that true Buddhism was about comprehending the "One Mind that alone is the ground of reality" (wei- hsin).