Sun Tzu’s 2500 year old book The Art of War contains a famous chapter on spies. However, Master Sun was not the only Chinese author to address this topic centuries before Westerners did. In fact, many Chinese authors built on his work. SPY Historian Mark Stout met up with Ralph Sawyer, the translator of the definitive edition of The Art of War and the author of The Tao of Spycraft, to discuss the sophisticated theory and remarkable practice of espionage in traditional China.