"Nearly half the volume is taken up by an elaborate Tibetan text edition of four chapters from the Phur pa bcu gnyis (PCN), a well-known but so far little-studied tantric text of the Nying-ma-pa school of Tibetan Buddhism, accompanied by a lengthy and highly technical discussion of the problems involved in editing texts of this type ...The introductory material of Mayer's book presents a masterly and original summary of the issues raised by these problems. The questions involved, those of canonicity, authenticity, vision and revelation, are vital to the understanding of Tibetan and other traditions of Buddhism in the west. Mayer's book is the first substantial attempt to present an overall picture of these issues ...Appealing to students of Tibetan Buddhism to broaden their horizons, Mayer provides impressive evidence of the advantages in doing so ...He sets this work in a broad intellectual framework drawn from the sociology of religion. The result is that his book is of value not only to related specialists but also to those in other areas concerned with similar problems. This work contributes to critical thought about canonicity in the Buddhist world generally and beyond it. " Professor Geoffrey Samuel, University of Lancaster