The Tibetan traditions generally divide the primary modes of exegesis on the Ratnagotravibhāga into two lines of transmission known as the analytic tradition (thos bsam gyi lugs) and the meditative tradition (sgom lugs). These two traditions originated with the Tibetan disciples of the Kashmiri master Sajjana—namely, Ngok Lotsāwa and Tsen Khawoche, respectively. Therefore, these two are also commonly referred to as the Ngok tradition (rngog lugs), representing the scholarly or analytic approach, and the Tsen tradition (btsan lugs), representing the more practice-oriented meditative approach. Alternatively, Jamgön Kongtrul, in his encyclopedic work commonly known as the Treasury of Knowledge, refers to Ngok's tradition as "the oral transmission of exposition" (bshad pa'i bka' babs) and Tsen’s tradition as "the oral transmission of practice" (sgrub pa'i bka' babs). Though it is likely the diverging motivations of these two figures in requesting these teachings from their mutual teacher that would set these traditions on their respective trajectories.
Ngok was the nephew of Ngok Lekpai Sherab, the founder of Sangpu Neutok, arguably the most important center for monastic education in Tibet during the eleventh to fourteenth centuries. Originally affiliated with the Kadam school, it evolved over the centuries into a Sakya and finally a Geluk institution, though throughout these changes it retained a strong association with rigorous philosophical study. It is regarded as one of the major birthplaces of Tibetan scholasticism. Ngok Lotsāwa spent much of his formative years under the tutelage of his uncle, who would found Sangpu when Ngok was only fourteen. After attending the Fire Dragon Religious Conference (me 'brug chos 'khor) that took place three years later in 1076, which coincided with his formal ordination, Ngok committed himself to traveling to India in order to train in Indic languages to become a translator. He then spent seventeen years studying with Indian and Kashmiri scholars before returning to Tibet and embarking upon an illustrious teaching career at Sangpu.
Tsen, on the other hand, who was almost four decades older than Ngok, sought out Sajjana and the teachings on the Ratnagotravibhāga for an entirely different reason. Rather than approaching the work as an object of study, which in Ngok's case would become the basis for a translation of the treatise, Tsen reportedly requested these teachings from Sajjana in order to make these instructions his primary practice in preparation for his own death ('chi chos). Unlike Ngok, he needed a translator to communicate with Sajjana, and though according to some accounts he had reportedly traveled to Kashmir with Ngok, a young man at the time, Tsen fortuitously enlisted the help of Zu Gawai Dorje to act as his interpreter. Together, the two of them received teachings on the entirety of the five Maitreya treatises from Sajjana, though it seems that the most thorough explanations were given on the Ratnagotravibhāga. Zu would later compose a commentary on the treatise based on Sajjana's instructions, as well as prepare a translation of the Dharmadharmatāvibhāga and associated works. While Tsen appears to have been the first of Sajjana's Tibetan students to return home and begin teaching, especially the Ratnagotravibhāga, to the community of Buddhists in the central Tibetan areas of U and Tsang, considering that the famed Bengali master Atiśa had been in Tibet since 1042 and was the first to translate the treatise along with his student Naktso Lotsāwa Tsultrim Gyalwa, it is likely that Atiśa would have been the first to teach the Ratnagotravibhāga on Tibetan soil.
In terms of Ngok and Tsen's respective approaches to the work and the divergence of the exegetical traditions they spawned, Tsen seems to have most closely transmitted the teachings of Sajjana. Although both considered the work to be an expression of the definitive meaning of the Buddhist teachings associated with the third turning of the wheel of Dharma, they differed considerably on what buddha-nature actually is and on whether it is possessed by all sentient beings and buddhas equally. For Ngok, buddha-nature was nothing more than another way of talking about emptiness, and in this sense he framed buddha-nature theory within the philosophy of the Madhayamaka school, which takes as the ultimate truth the lack of substantial existent entities. Based on the crucial verse I.28 in the Ratnagotravibhāga, he delineates buddha-nature in terms of its three aspects: resultant, inherent, and causal. The resultant was unique to the buddhas, while it is the causal aspect that is possessed by saṃsāric beings. All sentient beings have buddha-nature in the sense that they have the potential to become perfect in terms of a disposition (gotra), not in the sense that they contain within them an already-existent perfection. It is only in terms of the second reason, which asserts the indivisibility of suchness (tathatā), that both buddhas and sentient beings have buddha-nature in common. Tsen, on the other hand, following the teachings of Sajjana, advocated the position that buddha-nature is already perfectly present in sentient beings as it is in buddhas, and he equated it with the natural luminosity of mind. As such, buddha-nature already possesses buddha-qualities, which are to be revealed rather than produced. And while some later Tibetan traditions that counted Tsen among their lineage forefathers would consider him a Mādhyamika, likely in an attempt to distance themselves from an association with the denigrated view of Mind-Only, the only surviving work attributed to him is a brief teaching on the three natures (trisvabhāva) of the Yogācāra school. Hence, some Tibetan authors, notably Kongtrul in his Treasury of Knowledge, were inclined to associate Ngok's stance with the Madhayamaka and Tsen's with Yogācāra, specifically Mind-Only.
As for the descendants of these two figures and the influence of their traditions on the development of uniquely Tibetan positions on buddha-nature, the differences in their approaches to this topic—whether these are termed analytic or meditative, study or practice—are perhaps their most enduring legacy. In regard to the Ngok tradition, this style of exegesis took root at Sangpu Neutok, which continued to rise in stature over the course of several centuries. Sangpu maintained an intellectual tradition based on study and debate of Mahāyāna philosophies that was unrivaled in its heyday. It was also a remarkably fluid institution in terms of its affiliation, and its history is in many ways emblematic of the progression of Tibetan Buddhist scholasticism. Originally founded as a Kadam institution by Ngok Lekpai Sherab, it was a monument to the tradition founded by Atiśa. Though the ascendance of his nephew, Ngok, who returned from his seventeen-year sojourn in India as an accomplished scholar and prolific translator, certainly added to its prestige, its prominence as the Tibetan scholastic institution seems to have been fully established under the leadership of the eclectic Chapa Chökyi Senge. An accomplished and often controversial scholar, Chapa counted among his students the First Karmapa Dusum Khyenpa, Pakmodrupa Dorje Gyalpo, and the Sakya forefather Sönam Tsemo, who was the uncle of Sakya Paṇḍita. However, as time passed, Sangpu was enveloped by the rise of the Sakya school and later the Geluk, though for a period the two schools seem to have coexisted, albeit within a series of separate colleges, within its expansive compound. It suffices to say that many important Tibetan scholars studied or taught at Sangpu, including the Sakya scholar Rongtön Sheja Kunrik, the founder of the Geluk school, Tsongkhapa, and even the great Nyingma scholar Longchenpa, to name but a few. All of these figures, when studying the Maitreya works within the confines of Sangpu, would have done so through the lens of the Ngok tradition.
In regard to the Tsen tradition, it took a decidedly different tract and became a crucial tributary that flowed into the development of schools that established themselves outside of the mainstream of central Tibetan scholastic institutions—namely, the Kagyu, Jonang, and the Nyingma. In particular, it was the so-called other-emptiness, or zhentong, position, also referred to as Great Madhyamaka, that developed in these schools, especially the first two, that trace their lineage through the Tsen tradition. The sole extant work that is attributed to Tsen was titled the Instructions on the View of Other-Emptiness (Gzhan stong lta khrid) by its sixteenth-century Jonang redactor Kunga Drolchok, who claims the text as proof that other-emptiness existed in India and was thus not invented by Dölpopa. It is unclear whether Tsen would have conceived of himself as a zhentongpa, though he does appear to use the term Great Madhyamaka (dbu ma chen po). However, what his tradition clearly has in common with those that later espoused this stance was a positivistic view of the ultimate and a sense that the direct experience of this ultimate would fall within the purview of accomplishment that is the result of practice. Buddha-nature, in this view, is not merely a sheer emptiness but the innate luminosity that abides primordially within the minds of all, from sentient being to buddhas. The only difference is the presence or absence of the adventitious stains that obscure this luminous nature. And just as Tsen sought to implement this understanding in his practice, the followers of the Tsen tradition have tended to value direct experience over theoretical knowledge.
In summary, the exegetical traditions of Ngok and Tsen are not simply a matter of disagreements about what the Ratnagotravibhāga means. Rather, they represent different approaches to engaging with the treatise. They are also not merely the outcome of the repetition of the sayings of the masters who founded them, but rather the byproduct of people following in their footsteps and interacting with the teachings in a similar way. It is not as if everybody counted among the lineage of the Ngok tradition simply accepted his views and moved on, but rather that, like Ngok before them, they approached the teachings from the perspective of intellectual inquiry and scholastic rigor. Similarly, those zhentongpas that included Tsen as an early lineage holder likely saw in him a compatriot involved in their mutual efforts to experience the truth of buddha-nature for themselves rather than as someone whose teachings they upheld to the letter. Thus these traditions typify different approaches representative of divergent religious views, which are accompanied by their own specific attitudes, priorities, and the like. Nevertheless, their interest in the Ratnagotravibhāga unites them, even if the expression of that interest leads them down seemingly different paths.
- 'Jam mgon kong sprul, Shes bya kun khyab (Beijing: Mi rigs dpe skrun khang, 1982), 1:460.
- In the recensions available in the Tibetan Kangyur, however, he and his teacher Parahitabhadra are recorded as revisers of an earlier translation of the root text. For instance, see the colophon of Chos dang chos nyid rnam par 'byed pa, in bstan 'gyur (sde dge), vol. 123 (Delhi: Delhi Karmapae Choedhey, 1982–1985), 97.
- For details on Atiśa's translation, see Kazuo Kano, "Six Tibetan Translations of the Ratnagotravibhāga." China Tibetology 23, no. 2 (2014), 77–81.
- According to Kano, "As to the interpretation of Buddha-nature, on the other hand, Sajjana and rNgog hold different views, for Sajjana equates Buddha-nature with the luminous mind, which is not empty, while rNgog equates it with emptiness." Kazuo Kano, Buddha-Nature and Emptiness: rNgog Blo-ldan-shes-rab and A Transmission of the Ratnagotravibhāga from India to Tibet, Wiener Studien zur Tibetologie und Buddhismuskunde 91 (Vienna: Arbeitskreis für Tibetische und Buddhistische Studien Universität Wien, 2016), 239.
- According to Kano, "rNgog considers the RGV to be a Madhyamaka work and hence its teaching to be definitive. His position is made clear in the introductory passage of the rGyud bla don bsdus, where the RGV is identified as a treatise that explains sūtras of definitive meaning (nītārtha), whereas the other four treatises of Maitreya... are listed as treatises that explain sutras of provisional meaning (neyārtha)." Kano, Buddha-Nature and Emptiness, 249.
- Tsering Wangchuk explains, "The first reason is true only for enlightened beings, but only designated for ordinary beings; the second reason applies to both enlightened beings and sentient beings. Therefore, the two Kadam masters [Ngok and Chapa Chökyi Senge] argue that sentient beings do not have the tathāgata-essence from the perspective of either the first reason of the resultant essence or the third reason of the causal essence. Rather it is the second reason that becomes the central point for establishing the link between enlightenment and sentient beings. It is the middle reason that shows that sentient beings and tathāgatas are the same in their ultimate nature. In other words, the only thing that sentient beings have in common with enlightened beings is the ultimate nature of their minds." Tsering Wangchuk, The Uttaratantra in the Land of Snows: Tibetan Thinkers Debate the Centrality of the Buddha-Nature Treatise (Albany: SUNY Press, 2017), 17–18.
- Mathes cites Gö Lotsāwa's summary of the view of the Tsen tradition as, "The followers of the tradition of Tsen (Btsan) maintain that since the luminous nature of mind is the buddha nature, the cause of buddha[hood] is fertile." Klaus-Dieter Mathes, A Direct Path to the Buddha Within: Go Lotsāwa's Mahāmudrā Interpretation of the Ratnagotravibhāga, Studies in Indian and Tibetan Buddhism (Boston: Wisdom Publications, 2008), 33.
- 'Jam mgon kong sprul, Shes bya kun khyab (Beijing: Mi rigs dpe skrun khang, 1982), 1:460.
- Btsan kha bo che, Gzhan stong lta khrid, in Zab khrid brgya dang brgyad kyi yi ge, ed. Kun dga' grol mchog. Gdams ngag mdzod. (New Delhi: Shechen Publications, 1999), 18:170-171.
- See Kun dga' grol mchog, Khrid brgya'i brgyud pa'i lo rgyus, in Gdams ngag mdzod (New Delhi: Shechen Publications, 1999), 18:83-84.