At the risk of being ridiculed, I'll venture to say this: There's a big part of us that we don't fully know. All of us are trying to different things to find happiness. Above book proposes that Meditation has answers to most of the questions and talks about various Yogi's. This triggered a deep desire for me to know more. I learnt Meditation from a different organization and am very happy at where I am. This book started that journey.
Warning: There will be a bit of mysticism in all this. Take what your gut says and leave the rest.
[1] https://www.ananda.org/autobiography/ [2] https://www.yogananda-srf.org/