Vajrayana and Tantrism
The third category, Vajrayana or Tantrayana, which derives from Mahayana, is the school most closely associated with Tibetan Buddhism -- so integral a part of it that it has become virtually identified with the religion of Tibet.
The most mystical and esoteric of the schools, Tantric Buddhism is farthest from the common origin, and found little or no acceptance in southeast Asia, where it is sometimes not even considered an authentic school of Buddhism.
In a relatively early book (1894) on Tibetan Buddhism, L. Austine Waddell, an English observer, called it a cult whose name, he wrote, should more properly be Lamaism, as its divergence from Buddhism was so great.
Waddell thought that some of its higher rituals invited comparison with Catholicism (the resemblance is entirely superficial), but considered that many of its other practices were mere devil worship or sorcery.
Yet so distinctively different are some aspects of Vajrayana that even Professor Giuseppe Tucci, one of the most distinguished scholars in the field, used the term "Lamaism" interchangeably with Buddhism.
It might be described as an alternative route to enlightenment, requiring intense concentration and induction through special rites of initiation, but offering the hope of achieving enlightenment in accelerated time, perhaps even in a single lifetime: a sort of spiritual shortcut.
Rather than a training for mystical experience, aiming for a state of spiritual transformation, the yoga now popular in the West is often a system of physical exercise that makes use of breath control,
But although tantric yoga makes use of physical as well as mental discipline, it aims for much more than the physical benefits of flexibility and balance, or the tranquility of a calm mind in a calm body.
The yogin, transported to another state of existence, reaches the ultimate state of bliss, of beatitude. Sometimes referred to as "ecstasy," this is not the ecstasy of Dionysiac frenzy, but rather of perfect serenity, of still, untroubled consciousness.
The state of union with the divine is symbolically represented in Buddhist tantric art by a depiction of sexual embrace between the divinity and his consort in the attitude known as "yab-yum" (see below).
In depicting the highly symbolic and non-naturalistic visions of Tibetan Buddhist art, the artist was in an ideal sense a yogi, who could thus convey the type of spiritual, extra-sensory vision required for this art.
The concepts and practices of tantrism in the Buddhist universities of eastern India have been dated at least to the eighth century, from which time translations have survived, yet the theory and some of the texts may be several centuries older.
Some of the tantric masters who became known as mahasiddhas -- great adepts, master yogins -- were not necessarily attached to the monastic universities and the rules of the monastic orders, but were freely wandering yogins.
followers and scholars of Vajrayana Tantrism hold it to be authentically Buddhist in its essence, affirming the interdependence of all things and thus the illusive nature of duality, and the truth of the interaction of cause and effect.
Questions about the historicity of such practices, and whether they are meant to be viewed symbolically rather than understood literally, are complex and disputed.
Because of the risk of misinterpretation of Vajrayana texts and concepts, even when they are understood symbolically, and because of the risk of other misdirections, Vajrayana emphasizes the necessity of having a spiritual guide, a teacher or "guru," to lead one through the complexities of meaning and practice.