The phrase "Thirty-six Strategies" was written earlier than the year of writing, and its etymology can be taken from Tan Dao Ji (? -A.D. 436), according to the Biography of King Jingze of the Southern Qi Dynasty: "Tan Gong's thirty-six plans are the best policy, and your father and son should only listen to them." It means that defeat is inevitable and only retreat is the best policy.