1 Nephi 16:28

"And it came to pass that I, Nephi, beheld the pointers which were in the ball, that they did work according to the faith and diligence and heed which we did give unto them."

The ball is the liahona, a sort of compass given to them miraculously. This ball would only work when they listened to it. It is the same with modern day revelation. I can only get more knowledge when I heed what I already have.