This book is a must-have for yoga practicioners that want to go beyond simple asanas. This is a wonderful way to learn of hatha yoga's roots as a holistic system, and even put it into practice, since this book is a modern compilation of ancient Indian lesson-texts put into modern English. Hatha Yoga Pradipika means "Light on Hatha Yoga" (not to be confused with modern and lesser imitations that use that title). Holding this book in my hands feels like direct access to a rich history of the roots of hatha unscathed by "new age" ideas. Basically the book is about classical postures, breath control, and cleansing.
Interestingly, the book does not talk about food intake--basically says that it is not important to spend too much time thinking about what food to eat, how much, etc. (this is a nice change in a modern world that obsesses over food). However, it does go into length on the subject of cleansing the body using several methods, some of which are extreme, but some of which a novice could do with some courage.
Another interesting thing about the texts in this book is that although they are traditional, the focus isn't spent on spiritual concepts such as chakras, kundalini, or meditation, etc, it even rarely mentions relatively popular yoga terms such as prana or nadis. As it is well-known about hatha, the people who practiced these ancient rituals believed that persons could not reach enlightenment through stillness and meditation, but instead, through physical asana and purification. There are interesting and clear ideas concerning this inside the book as well.