Having attended Isha's Inner engineering program many years back, I knew what the book would talk about in a broad sense. Several weeks after the program, I remember feeling extremely calm and kind, to myself and to people around me. Over years, this intrinsic calmness paved way for noise and imbalance as entropy took over.. When I saw this book on Amazon, I knew I needed to get it. Obviously, the book is not effective as the program itself, but a great place to start. ultimately knowing the concepts can only get you so far, but what is required is to experientially realise them. I have never experientially realised any of these rather 'difficult' concepts except during the Inner engineering program. I hope I am able to shrug off my laziness and put in the required time/ energy that the sadhanas or practices mentioned in the book require. Recommended to every seeker as a starting point. It will not answer all your questions, but can be a great place to start.