The main object of this book is to discuss the science of Yoga in as simple and rational a manner as possible, and also to debunk some of the nonsense that continues to be said and believed on the subject. A must for all those are eager to clarify their conception about Yoga.
Be strong! Don't talk of ghosts and devils. We are the living devils. The sign of life is strength and growth. The sign of death is weakness. Whatever is weak, avoid! It is death. If it is strength, go down into hell and get hold of it! There is salvation only for the brave.
-Swami Vivekananda