The books that help you most are those which make you think that most. The hardest way of learning is that of easy reading but a great book that comes from a great thinker is a ship of thought deep freighted with truth and beauty.
That's an amazing feeling to walk onstage and you're not thinking about anything you're not thinking about your lines or what you're supposed to do - your body your brain knows so there's freedom. There's not fear there's not nerves.