The third volume of this landmark series presents the vajrayana teachings of the tantric path. The vajrayana, or "diamond vehicle," also referred to as tantra, draws upon and extends the teachings of the hinayana and mahayana. As with the hinayana and the mahayana, the formal acceptance into the vajrayana is marked by a vow, in this case the "samaya" vow. There is an emphasis at this stage on the student-teacher relationship and on the quality of devotion. Generally, students must complete preliminary practices, called "ngOndro," to prepare themselves for initiation into the vajrayana path...