As rivers have their source in some far off fountain, so the human spirit has its source. To find his fountain of spirit is to learn the secret of heaven and earth. In this fountain of mystery, spirit is eternally present in endless supply. Anyone can avail himself of it for the refreshment and the unfolding greatness of his own spirit by the earnest practice of concentration, but to do so he must devote himself to the effort with wu-wei of mind and sensitive expectancy.