" How much actual cash that original DESIRE of Barnes' has been worth to him, I have no way of knowing. Perhaps it has brought him two or three million dollars, but the amount, whatever it is, becomes insignificant when compared with the greater asset he acquired in the form of definite knowledge that an intangible impulse of thought can be transmuted into its physical counterpart by the application of known principles. "

― Napoleon Hill , Think and Grow Rich