Sun Lu-t'ang's skill and books did much to spread the internal rationale. In an introduction to Sun's Ch'uan-i Shu Cheng (The Real Explanation of Boxing, 1929), Wu Hsin-ku stated that "youngsters think boxing is merely a weapon to be displayed with foolish courage and youthful vigor" and that Sun had written the book to offset this and to present the true art
Source Smith, Robert. Hsing-i, Chinese Mind-Body Boxing ISBN 1556434553