You don't have to know alot of things for your life to make a lasting difference in the world. But you do have to know one great thing, and then be willing to live and die for it.
The people that make a durable difference in the world are not the people who have mastered many things, but who have been mastered by one great thing.
If you want your life to count...you don't have to have a high IQ. You don't have to have good looks or riches or come from a fine family or school.
Instead you have to know one great, majestic, unchanging, obvious, simple, glorious thing -- and be set on fire by it.