Source: As quoted in Perceive This! : How to Get Everything You Want Out of Life by Changing Your Perceptions (2004) by Kevin A. Martin, Ch. 9, No Bar Too High!, page 64

Complete Sentence: Somehow, I can’t believe that there are any heights that can’t be scaled by a man by a man who knows the secret of making dreams come true. The special secret it seems to me is summarized in four C’s. They are Curiosity, Courage, Confidence and Constancy. And the greatest of all is Confidence. When you believe in a thing, believe in it all the way, implicitly and unquestionably.