Forty five years of actual trading experience and market research by W.D. Gann have made this book possible. He writes from practical application and not theory. Forty five years of actual trading experience and market research by W.D. Gann have made this book possible. He writes from practical application and not theory.The author writes: "In this book I have revealed some of my most valuable rules and secret discoveries never published before, in hopes that others will work and study hard to learn and apply these rules. If they do, speculation and investing will no longer be gambling but will become a PROFITABLE PROFESSION.