A Series of Lessons in Raja Yoga - William Walker Atkinson

The Book talks on the internal world of the self. The real nature of the subconscious mind, the way to control it, how ego comes into play and most frequently asked questions like "Who am I" are attempted to answer. (Summary by Uday Sagar)
Note: William Walker Atkinson wrote this book using the pseudonym Yogi Ramacharaka.