An incredibly detailed book describing in detail the practices Layayoga teaches to reach energy for the whole body, both physical and divine. It's strength is in its detailed descriptions of the fundamental ideas in Layayoga, the chakra system, and the concentration practices.
The amount of detail is also a problem for the book. It is not for beginners. Readers need to be ready for an immersion into Sanskrit terms and non-Western concepts. If they can handle the terms, concepts, and academic writing style, readers will find deep understanding of the techniques.
I believe that there are paths to understanding non-physical reality that are more in tune with Western culture. And perhaps there are paths that do not focus so much on the intellectual aspects of the work. But this is knowledge that deserves to be preserved and studied. As such, this is a valuable book.