I found this one, and the first comment on it - also written by a yoga 'expert' - really caught my eye. I'm reproducing it below, with the interesting bits bolded.
I don't know about you - and I will wait to read the book first before I really start having a fixed opinion about this - but at this stage, it seems like yoga is more and more of a kosher pig, that really can't be 'kosher' in any sense of the word, no matter how it's cooked, killed or dressed-up.
One potential clue to whether it's really good or bad is the 'mysterious serpent power' being referred to below. Is that setting off any associations with the Garden of Eden for anyone else?
'Jussst ssssstretch a bit Eve, and then you'll feel so good. Onccccccce you know how to do down dog, you won't need to go and talk to God any more...'
We live in a such a superficial world, that even the most idolatrous religious practices can be re-packaged as 'exercise', and we barely bat an eyelid. This stuff may be making you more flexible, but at what cost to your soul? And your connection to God? And your ability to really live, relate and feel like a Jew?
That's the questions I'm asking, and that I'm hoping to start finding some concrete answers to, shortly - and I welcome your input! But in the meantime, I'm not heading off to a yoga ssssssstudio anytime soon.
Feuerstein is in one sense a true believer. He has devoted his life to the study of yoga and attendant phenomena, in particular Hinduism and the broad Tantric tradition...
The book begins with a thorough definition of yoga and then an overview, and then its inescapable conjoining with Hinduism. This is "Part One: Foundations." Then Feuerstein looks at "Pre-Classical Yoga" and overviews the entire Vedic tradition including the yoga of the earliest Upanishads, culminating in its expression in the Bhagavad Gita. Then in "Part Three: Classical Yoga," he comes to Patanjali and the yoga of the eight limbs, the famous yoga of the aphorisms. Part Four is "Post-Classical Yoga" from the later Yoga-Upanishads from the Middle Ages in which the focus is on bhakti, technique, mantra and meditation. It is here that Western readers will find much that is new, or at least not readily available in English. And it is here that a non-dualistic yogic philosophy (as opposed to the dualism of Patanjali) holds sway. Part Five is on tantrism and "Yoga as Spiritual Alchemy." It is in this last part that the so-called "subtle body," with its nadis and pranas, its cakras ("psychoenergetic centers") and the mysterious serpent power of kundalini, is explored in depth. Here too we have the ritualistic practice of the five forbidden things from tantra yoga, the infamous "left-handed path." Here is Feuerstein's take: "Practitioners of the left-hand path (<vâma-mârga>)--vâma means both "left" and "woman"--know they are breaking profound social taboos, and their only justification for their conduct is that their goal is not sensual gratification but self-transcendence in the context of bodily existence." (p. 484)
To me--and I have studied and practiced yoga for 28 years--yoga is first and foremost a profound psychology, a way of life that has evolved along with the human experience, from the prehistory to today, a guide on how to live that has come down to us in part (only in part: so much has been lost) as a philosophic and religious tradition. Feuerstein's book is at once a great reference and a heart-felt exposition on the power of yoga to transcend this world in which we are enveloped in the "food sheath," where we are both the eater and the eaten, but with our eyes on the stars.
--Dennis Littrell, author of "Yoga: Sacred and Profane (Beyond Hatha Yoga)""