There are many books on yoga but few give the needed breadth and depth. Much fewer is able to convey subject simply, in a way that the layman can understand. Most books touch on subject superficially, focussing just on beautiful pictures of asanas.
This is one of those books I would recommend, whether you are a teacher or a student. Mark Stephens is able to cover breadth yet he is able to do this simply so that interested student can use the basic understanding gained here to explore further and deeper. I like the book for its thoughtful and insightful approach to the various aspects of yoga which may seem unaccessible to the layman. The author touches briefly yet succinctly on the ancient history of yoga and its modern developments and variations, giving the essence on the yoga scriptures and philosophy, and approaching learning and teaching with empathy. In short, there is a bit of everything yet lends some depth because of the author's own depth of experience as a teacher.
I would not fault the book for being short on some areas (such as anatomy) as this is a general book that aims to give a broad view of the subject. Interested students and aspiring teachers would gain much reading this as it is foundational knowledge and understanding - put in a very readable way. The author's sharing of this own vast experience in such an unassuming way is valuable.
I share Mark Stephen's approach in my own teaching, going back to the core philosophy and approach of yoga even in teaching asanas, and putting asanas in its proper perspective. There is an over-emphasis on asana practise in the market, so that it becomes just like another other exercise. Worse, a lack of understanding of the real value and purpose of yoga asana causes many students and teachers to push themselves to the point of injury, causing undue stress.
I highly recommend this book to students and teachers. It helps your navigate through the vast field of yoga and the great variety of hatha yoga styles available today.
The other book that is a must read is TVK Deshikachar's The Heart of Yoga, which also stresses on understanding the purpose and value of asana and yoga, as well as the need to be empathetic to your students. These 2 yoga books are sorely needed in current times, when yoga has become a fad but few understand its real purpose, much less how to teach it, and to educate others properly.
Some excerpts:
(On tradition vs innovation)
"We can look at these traditional schools as spanning a continuum from relative insistence on teaching and practicing in a prescribed way to more open and eclectic approaches in which teaches feel a sense of creative freedom. Many observers have characterized the one extreme as fostering dependence on authority, diminishing spirit and humanity in the practice, and the latter as drifting into body sculpting or other practices that are more exercise than yoga, where traditional ideas of yoga virtually disappear. Beautiful and authentic teachings can be found throughout the spectrum, as can sloppiness and practices that result in a high incidence of injury."
(On the great variety of Hatha yoga styles today)
"One of the challenges in describing some yoga traditions is evaluating the veracity of claims - the verifiable truthfulness about the origins and evolution of their practices. Many famous yogis claim to have received a yoga teaching directly from a divine source or from ancient writings that have since been lost. The believe that we are teaching or practicing in a tradition that was divinely inspired can be a powerful motivation to accept that tradition and create a sense of superior ordination. Yet whether or not the many fascinating stories about the creation or evolution of a style are true, what matters is whether the substance of the teachings has integrity. As a teacher, it is important to teach from a place of truth as you best feel it, know it, and understand it, ultimately this derives form intensive study and open-minded exposure to different traditions as well as experience on your mat and practice in the art of teaching. There is no question that much of the received wisdom of tradition was transmitted orally, often through memorization of songs or slokas. It may well be that every claim is true, although many stretch even the most tolerant imaginations, especially when considered in context of other claims made by the guru that test credulity. A few things we do know can be applied in thinking about this and navigating our way through the traditions."
(on the various teaching styles)
"The best teachers are those attuned to their students' needs and capable of teaching in a way that addresses those needs while safely introducing them to new challenges and possibilities. If, as a teacher, you are committed to one approach, then acknowledge that to yourself while appreciating that you will have many students for whom another approach is probably better suited. Broadening your repertoire of skills and knowledge will enable you to more easily recognize these fits and help you prepare to respond in the most effective, appropriate, and honorable way. Sometimes that might involve offering variations and modifications, other times suggesting a completely different practice or teacher. If you are committed to a certain lineage, this will help define who you are as a teacher. If you are more independent in your approach, how you choose to relate in your teachings to the many lineages and stules of yoga will go far in defining your own teaching. But no matters your perspective in relation to gurus, systems, and approaches, what will always most define you as a teacher is how you choose to relate as a human being to your students.With compassion, knowledge, and skills, you will be the best teacher you can be."
(on Bikram yoga)
"Perhaps more than any yoga teacher, (Bikram) Choudhury is unabashedly boastful in describing his personal accomplishments both on the mat ("I am beyond Superman") and off the mat, frequently reminding others of his financial success....Railing against other forms of Hatha yoga in the West as ill-informed, inventive, and dangerous, Choudhury asserts that his method is "the right way" to do yoga. Asserting that "using props to help you do the postures only makes matters worse and not better," he warns that Americans are "getting rippped off, even getting hurt" in practices that deviate from the true system of yoga he claims was given in Yoga Sutras...Ironically, the one and only prop allowed by Choudhury - an extremely heated room - is itself a source of injury. Stretching in an environment heated to such an extreme as in Bikram yoga allows a person to stretch much further than would otherwise be possible for his or her body. The problem is that this extended stretching ability is often beyond what the body is ready for, often resulting in injuries....Bikram yoga responds well to the powerful impulse in Western culture to feel quick results from any effort."
I share this view on Bikram Yoga too. Every practioner has a freedeom of choice, and I encourage those who find Bikram yoga helpful to continue along that path but I also advise discretion and care as Bikram's style can be punishing for beginners, those not already quite fit, and those already with prior injuries. Bikram Choudhury's approach to yoga is extremely commercial compared to others I have seen, and patenting his posture sequence in USA is contrary to the spirit of yoga that the teachings are a gift to mankind. His derisive comments of other styles and approaches is too prescriptive and narrow.