Though the theory of buddha-nature is more readily associated with certain
Mahāyāna sūtras and related treatises, such as the
Ratnagotravibhāga, in the Tibetan tradition there also developed a strong association between this concept and the
Vajrayāna. For instance, terms like
tathāgatagarbha and
sugatagarbha also appear in tantric literature, and in the
Jonang tradition Dolpopa's development of his famed view of
other-emptiness (
zhentong) was directly linked with a profound realization he attained through his practice of the
Kālacakra Tantra. For the
Kagyu, the
Ratnagotravibhāga has long since been described as a "bridge between
sūtra and
tantra," and for the
Nyingma sugatagarbha is commonly used throughout much of the revealed tantric corpus of its treasure tradition. There are even proxy terms for buddha-nature used in tantric literature, such as the
causal continuum (
rgyu'i rgyud), which at the level of Highest Yoga
Tantra is symbolized by the syllabic compound
Evam, representing the bliss of union. Even the notion of
luminosity, often rendered literally as "
clear light" in translations of Tibetan tantric works, can be taken as analogous to descriptions of buddha-nature restructured to conform to the methodologies of tantric praxis. Therefore, buddha-nature remained a crucial concept for the Tibetan
Vajrayāna traditions in which it found expression in a variety of literary forms—some of them familiar and others more in tune with the esoteric nature of
tantra.