A little over a year ago, I had two identified.
There are three books that I think every adolescent (or adult who missed them) must read to function intelligently in modern society. They are the Three Critical Life Books listed here: http://chirontraining.com/Site/Reading.html
"Think and Grow Rich" by Napoleon Hill suffers from an unfortunate title, is extremely dated... but it lays many things out in cold and usable terms. Hill was given an assignment, by one of the richest and most powerful men of his time, to find out what successful people had in common. What the difference was between success and failure. He came through in spades and every person, every last person who has gotten off their asses and followed his advice, has become a standard deviation better. At least.
"The Richest Man in Babylon" by George Clason also suffers from its period. But it explains how money and wealth work in a usable way. It is an unparalleled pardigm-shifter and will help anyone, even people like me, raised to be poor and understand the world the way poor people are taught to understand it, to compete in the real world. And, if you read it right, to compete without jealousy.
"How to Get Control of Your Time and Your Life" by Alan Lakein is the time management book on which every other time management book seems to be based. Others may have played with the nuances, but Lakein is the one who laid out the priniciples. If you are tired of drifting through life and want to take the tiller, this is the book.
The first time I ever heard the phrase "Sacred Question" was in a Tom Brown course. It was a question of exceptional power. A question that, if you asked it, could change defeat into victory and forever make you grow as a human being: "What is the lesson here?"
I love grappling, and one thing I tell students is that it is impossible to lose a grappling match. If you tap your opponent, you have won. And if your opponent taps you, you have learned. And learning in a class is more valuable than winning. What have you learned, or "What is the lesson here?' turns defeat into growth.
The second sacred question I discovered was critical when dealing with criminals. When I was a rookie, a crusty old sergeant told me, "If one of these guys walks up and says 'good morning' you ask yourself, 'what does he want?'". That sounds cynical, but on a deep and useful level, if you can figure out the true motivation, if you can discern what the real problem is (as opposed to the professed problem) you have a super power. So the second sacred question I discovered (but the one I think is most important and therefor the first) is: "What is the goal here?" If I truly know my goal and the opponent's goal (and most people do NOT known their true goal) it is better than Sun Tzu's advice to know yourself and your enemy. It is a game-changer like no other.
Anyway, I've been re-reading Lakein, and he put forward the Lakein Question: "What is the best use of my time right now?" Time is a limited resource. In a very real sense it is all that we truly have and we have a very limited amount. This simple question, applied consistently and maybe constantly, has incredible power to change your life. To change every aspect of your life.
I nominate Lakein's Question as the Third Sacred Question.
Edit. I can't believe I typo'ed the title.
Getting Killed Second is Still Not a Win - Sometimes I get asked "What do you think about this drill or technique"? My standard answer "What happened to get to this point so this could happen"? Her...
2 weeks ago