This work has been on my reading shelf for a little while, but it came to the top of the list as it was recommended reading for a course I enrolled on.
The book is a translation and commentary on various yoga source texts from Vedas through Hatha Yoga Pradipika, so maybe 1500 bce to 1500 ce. As such it joins a crowded market place for translations and commentaries, but what sets the writing apart is that it is compiled on a thematic basis across texts, rather than the more common approach of translation and commenting on a textual basis.
I haven’t seen these thematic basis before, and it works well in my view. Taking common themes like definitions of Yoga, Posture, Breath, Yogic Body and a host more, the authors comment comparatively on how these subjects arise in the different source texts, and then translate and comment on individual sections / verses.
Theres no getting away from this book being quite a complex work, and its 500 or so pages bear testimony to this, and its not, I feel, a beginners primer on Yoga Philosophy (or, as I heard it described recently, yoga Philosophies as there are many). However for someone with a initial understanding of the philosophical background to yoga, this is a commentary that adds a lot of value and enriches knowledge, and on that basis its a publication I would recommend.