A formative influence upon the Vajrayoginī cult was that of non-dual Shaivism. Pioneering research in this area by Sanderson has shown that the highest Buddhist Tantras be startlingly reliant upon non-dual Shaiva sources; so much so that it amounts to no less than what he calls ‘pious plagiarism. Sanderson estimates that in the root text of the Chakrasamvara tradition, Laghusamvaratantra, ‘long passages, amounting to some two hundred verses, nearly a third of the whole, can be seen to have been redacted from Shaiva originals,’ which – since this part of Shaiva canon is itself only partly preserved – must indicate an impressive debt.
The Shaiva cults that leave their imprint most strongly upon the higher and highest Buddhist tantras are those belonging to the Mantrapīṭha and the Vidyāpīṭha, both of which are divisions within that stream of Shaiva dispensation termed the Mantramārga, ‘path of mantras’. Worship within the Mantrapīṭha was of a type of Shiva called a ‘Bhairava’, a wrathful, cremation-ground form of god in union with an equally terrible consort, such as Svacchandabhairava (or Aghora) and his consort, Aghoreśvarī. The cremation-ground elements are even more in evidence in the Vidyāpīṭha, where they relate principally to esoteric cults based upon feminine power (śaktiḥ) such as those of the Trika and the Krama. The Trika focuses on three goddesses, Parā, Aparāand Parāparā, who have subordinate consorts in Bhairava forms and retinues of male and female deities. The Krama cults manifest fierce forms of the goddess Kāla. In one of the highest forms of non-dual Shaivism, the goddess is worshiped within a maṇḍala of twelve identical Kālīs; she appears alone without any consort, indeed, stamping upon the corpse of Bhairava, or wearing parts of his dismembered body for her ornaments. The Vidyāpīṭha perceived itself as related but superior to the Mantrapīṭha, just as the Buddhist Yoginītantras perceived themselves as related but superior to the Yogottaratantras. It is from the Vidyāpīṭha tradition that the Yoginītantras drew most heavily.
Sanderson has pointed to a number of ways in which the Buddhist tantra is indebted to the Shaiva tradition, and what follows is a brief summary of his findings with just a few examples.
First, the Buddhist Tantra borrows on the textual level. One way it does this is to draw on Shaiva scriptural titles, with little or no adaptation to the new Buddhist context. For example, the Buddhist title Yoginīsaṃcāratantra points directly to the Shaiva chapter title Yoginīsaṃcāra (in the Kālī-centered Jayadrathayāmalatantra). Another Buddhist tantra title, Sarvabuddhasamāyogaḍākinījālasaṃvara, is closely influenced by the titles of two Shaiva works, the Sarvavīrasamāyoga and the Yoginījālasaṃvara, while the Buddhist Hevajraḍākinījālasaṃvara again draws on the Shaiva title Yoginījālasaṃvara.
As well as relying on Shaiva nomenclature, great portions of the text are drawn wholesale from Shaiva sources. For example, Sanderson has shown that the root Chakrasamvara scripture draws directly on Shaiva sources in the chapter teaching how to identify and distinguish members of the various families; thus the Laghusamvaratantra describes the characteristics of a class of yoginīs known as ‘lāmās’ by drawing directly on the Shaiva Siddhayogeśvarīmata, and on the same theme the root text draws directly from the third ṣaṭka of the Jayadrathayāmalatantra; it also incorporates portions from Trika texts such as the Niśisaṃcāra and the Tantrasadbhāva. The so-called explanatory tantra to the root text, the Abhidhānottaratantra, has drawn directly on the Picumata – Brahmayāmalatantra for the rules (samayas) that bind initiates; the Saṃvarodayatantra draws also upon the Picumata for the classification of skull bowls. As one may expect from such a heavy reliance upon the Shaiva texts, apart from the stunning number of parallel verses, there is also a high degree of overlap in stylistic convention and stereotypical expression, such as the common introduction: ‘Next I will explain……’ (athātaḥ saṃpravakṣyāmi). In these ways, the Shaiva texts serve not just to provide concrete materials on various topics but become structural models for the new Buddhist compositions. This affected even the most unique element of any tantric practice, the mantra, which may not only be written down according to Shaiva conventions for preserving mantras intact but are themselves in the style of the Shaiva Vidyāpīṭha. A clear example of Buddhist recycling and adaptation of a Shaiva mantra is found in the Guhyavajravilāsinī sādhana.
Second, the Buddhist tantras have taken their wrathful and erotic orientation from Shaiva praxis. The terrifying, cremation-ground character of the higher Buddhist tantras has its roots in Shaiva mythology. According to the myth described variously in the Purāṇas, the original skull observance (kapālavrataṃ) or ‘great observance’ (mahāvrataṃ), was the result of a quarrel between Brahmā and the Vedic form of Shiva, Rudra. When Rudra ends the matter by plucking off Brahmā’s head, he finds he has committed the heinous crime of slaying a brahmin (brahmahatyā). He is then forced to undergo a period of extreme penance in which he lives in exile from society, dwells in cremation grounds, smears himself with ashes of the dead, and begs for food using a bowl made of human skull. Orthodox Dharmaśāstra states that brahmin-slayers can only expiate their offense through a period of twelve years in exile, by inhabiting cremation grounds and by carrying a skull bowl (kapālaṃ) and skull staff (khaṭvāṅgaḥ) when begging food. The mythical role model of the penance of Rudra became the direct inspiration for early ascetic cults in the atimārga (‘outer path’) stream of Shaivism, such as the Pāśupatas (dating from the second century) and in particular their more extreme offshoot, the Lākulas. Lākula ascetics adopted the outer appearance and behavior of Rudra as part of a progressive series of practices aimed at complete immersion in the deity. Skull observances were also adopted by ascetics in the mantramārga stream of Shaivism, who moved away from the liberationist goals of the atimārga, choosing instead to aim for the acquisition of supernatural power (bhoga). They wore bone ornaments and carried the skull staff of Kāpālika observance, but modeled themselves instead upon terrifying cremation-ground ectypes of Shiva, whom they worshiped with impure substances such as alcohol, blood, and sexual fluids.
The Buddhist initiate into the esoteric cults of the Yoginītantras likewise performed a skull observance, known as the ‘vow of the observance of heroes’ (vīracaryāvrata), or the vajra skull observance (vajrakāpālikacaryāvrata). As in the Shaiva tradition, this was based on the practitioner’s inner identification with his chosen deity and involved worship of the deity with impure substances. In Abhayākaragupta’s description of the ‘vajra skull observance’, the male practitioner wears the attributes of the Buddhist deity Chakrasamvara. He adorns himself with a garland of skulls, a tiger skin as the lower garment, a Brahmanical thread made of sinews or human hair, a headdress, a garland, a vajra, armlets, anklets, and little bells, and he visualizes his consort as Vajravārāhī. While the Buddhist observance, like the Shaiva counterpart, also brings the promise of supernatural attainment (siddhi), the goal is ultimately that of enlightenment.
Another feature of the Vajrayoginī cult that owes its origin to non-dualistic Shaiva developments is its emphasis on the worship of female deities. In the Vidyāpīṭha traditions of Shaivism, the center of the cremation-ground cult on families of “mothers”: classes of wild yoginīs who drink blood, wear skull ornaments and are enticed by impure offerings of bodily and sexual excretions (Sanderson 1988: 67off.). In this context, the central goddesses of the Trika rise above their male consorts in status to become the chief deities of the maṇḍala, while esoteric forms of Kālī emerge entirely from the embrace of their consorts. As a sign of her supremacy, Kālī subjugates her former consort by trampling him underfoot. We will see Vajravārāhī and Vajrayoginī rise above the male forms in the same way in the Buddhist tradition, and with the same iconographical symbolism. Within the highest Buddhist tantras, however, the iconographical borrowings take an unexpected turn, as it is not the deities of outmoded Buddhist systems that are trodden down, but the Shaiva gods themselves. Thus, while the motif of subjugation is another example of the Buddhist reliance upon Shaiva norms.