Craig draws upon his extensive working knowledge of the Yoga of the Left (he is the rare recipient of both the Veda Kovid and Yoga Charya titles) to create a refreshingly concise introduction to the key concepts of the Hindu mysteries associated with Kali. I personally found the book's most invigorating aspect to be its central concept of Kaivalya, which the author defines as "The state of unconditional individual existence in the Self/Atman literally meaning 'aloneness.'" Those familiar with the more conventional Eastern teachings will note how radically Kaivalya departs from the common aim of dissolving the Self into the cosmic source. And while many contemporary western sodalities who claim to follow the Sinister Path might embody certain Kaivalya traits, Williams is quick to advise that the antinomian solipsism that runs rampant through many western LHP occult circles is anathema to authentic Vama Marg praxis.
Perhaps what is most "radical" about the book is its educated iteration of the importance of the Guru-student relationship. In this, a time of what Craig refers to as "cafeteria-style" Initiation, wherein aspirants merely skim the surface of any number of traditions, cosmologies, or paths in order to cobble together a mire that does little more than gratify their ego, Craig Williams illuminates the importance of not only having an objective teacher but also of personal humility when undertaking Left Hand Path Initiation.
Also contained in the book are rituals centering around Pratyahara ("withdrawal of the senses") and the Saturnian current. Cave of the Numinous marks the first in a series of Tantric Physics books by the same author. It is an auspicious beginning to what is sure to be an important series for anyone who harbours a passion for Gnosis.