明世宗是一位非常迷信的皇帝，其中有位叫藍道行的算命仙，是最受他寵愛的道士，這是因為他曾經通過世宗的一項考驗。有一次，世宗為了測試藍道行的功力，就派一位太監送密函給藍道行，送到時就將信燒掉，並叫太監對他說：「密件中寫著皇上要問你的問題，你法術高強，請把答案告訴我，好讓我回去稟告皇上。」藍道行一聽急了，心想：「沒看，怎麼會知道信裡寫什麼？這一次要被砍頭了。」突然靈機一動，藍道行就跟著太監去見世宗。藍道行對世宗說：「屬下懂得招神的法術，不過您今天派來的太監不夠虔誠，神明不肯現身回答問題，小的自然答不出來，大膽請皇上再派一位虔誠的太監送信來。」由於世宗太迷信，就派另一個太監送信，藍道行早有準備，在燒信前，趁太監不注意時，將真信與預藏的假信對調，燒掉的是假信，信裡的內容就被藍道行知道了。世宗不知情，聽到太監帶回來的正確解答，從此對藍道行的法術更加的相信。
三十六計之第二十五計：偷梁換柱
就是在神不知鬼不覺當中，將東西換過來，欺騙對方，來取得勝利，也就是調包的意思。
Ming Shih Zong was a very superstitious emperor. He had a favorite fortune teller by the name of Lan Dao Sing, who once passed a test set by the emperor and thus won his trust.
Once, in order to test Lan Dao Sing, the emperor sent a eunuch to deliver a confidential letter to him. Upon arrival, the eunuch burned the letter before it was opened and told Lan Dao Sing, "The letter contained the questions that the emperor wanted to ask you. You are the expert in magic. Please tell me the answers to the questions so that I can report back to the emperor." Hearing this, Lan Dao Sing started to panic. He thought, "How could I know what was written in the letter without reading it first? The emperor is going to have my head for this." But suddenly he came up with an idea to save the day. So he followed the eunuch to see the emperor.
Lan Dao Sing said to Ming Shih Zong, "I know how to call upon the supernatural powers. But the eunuch whom Your Majesty sent today was not devoted enough, so the gods refused to show me the answers. May I request Your Majesty to send your letter again using another eunuch who is more devoted as a messenger?" Because the emperor was so superstitious, he agreed to send another one. This time, Lan Dao Sing was well prepared. Before the letter was burned, Lan Dao Sing had switched the real letter with a fake one when the eunuch was distracted. Thus, Lan Dao Sing learned the content of the letter through guile and gave the emperor the correct answers. Ming Shih Zong was not aware of his trick. And so he came to have even more faith in Lan Dao Sing's magic.
Strategy 25: Replace the Beams with Pillars
While your opponent is unaware, steal the real thing by swapping it with a fake one, thereby achieving your goal through deceit.
