三國時，魏明帝死前任命曹爽為輔佐大臣，幫年僅八歲的太子管理朝政，曹爽為了獨攬大權，就建議廢帝以及立司馬懿為大傅，希望藉由升官，將司馬懿的大權搶過來，司馬懿知道實力不如曹爽，便裝病請假回家休養。
曹爽不放心便派李勝到司馬懿家中看看是不是真的生病。李勝看到婢女扶著兩眼無神、走路不穩的司馬懿到大廳見客，李勝對司馬懿說：「我要到荊州當刺史，今天是來向您辭行的。」司馬懿有氣無力的說：「并州離胡人很近，你要小心安全喔！」李勝回答：「是去荊州，不是并州。」司馬懿又說：「什麼！原來你已經去過并州了！」李勝心想他真的病得不輕，這時，又看到婢女端著藥出來，司馬懿喝藥流得嘴角和衣服都濕了，完全看不出以往威風八面的英姿。
李勝回去報告曹爽自己看到的景象，並說：「我看他大概活不了多久了，不用擔心。」曹爽大笑三聲，從此再也不管司馬懿。
第二年春天，司馬懿趁著曹爽等人去京城祭祖時，便發動政變，揭發曹爽兄弟的惡行，更以陰謀叛變的罪名，將曹爽兄弟等人全部處死，魏國政權又再度回到司馬懿的手中。
三十六計之第二十七計：假痴不癲
外表上好像裝瘋賣傻，什麼事也不做，其實一方面是怕對方起疑心，一方面在暗中等待有利時機，再一鼓作氣出擊。
During the Three States Period, before Emperor Wei Ming died, he appointed Cao Shuan as the regent to assist his eight-year old crown prince govern the country. But Cao Shuan had more ambitious plans. After Wei Ming died, Cao Shuan tried to seize power for himself, by suggesting that the child emperor be dethroned and that Sih Ma Yi be appointed prime minister. Cao Shuan hoped that by promoting Sih Ma Yi from a general to a prime minister, Sih Ma Yi would have to cede military command of the army. This way, Cao Shuan could then appoint his own man as general and seize control of the military. Sih Ma Yi knew that he was too weak to confront Cao Shuan at the moment, so he pretended to be ill and took a sick leave in order to thwart Cao Shuan's scheme.
When Cao Shuan heard the news that Sih Ma Yi was sick, he was not convinced that Sih Ma Yi was really sick. So he sent Li Sheng to visit Sih Ma Yi in order to verify the story. When Li Sheng visited Sih Ma Yi, he saw that Sih Ma Yi was a haggard man who needed a maid to steady him as he walked out to receive Li Sheng in the living room. Li Sheng told Sih Ma Yi, "I was appointed an official in Jing province. I am on my way there to serve my term. Today I came to pay my respects by saying farewell to you." Sih Ma Yi said with a faint voice, "Bing province is very close to the border with barbarians. You must be very careful." To this Li Sheng replied, "I said Jing province, not Bing province." Sih Ma Yi then said, "Oh, so you have been to Bing province too…" Li Sheng thought that Sih Ma Yi was seriously ill. At this time the maid took the medicine tray into the living room to feed Sih Ma Yi his medicine. Sih Ma Yi slobbered medicine all over his mouth and his clothes while taking the medicine. There was none his past glory and grace.
Upon returning, Li Sheng reported to Cao Shuan what he saw during the visit. He said, "I think Sih Ma Yi is finished. I believe his days are numbered. There is no need to worry." Cao Shuan laughed out loud and paid no attention to Sih Ma Yi from that day on.
The next spring, while Cao Shuan left the capital for ancestor worship, Sih Ma Yi launched a coup d'etat and disclosed the crimes by Cao Shuan and his gangs. He also accused them of treason and executed all of them. This was how Sih Ma Yi won back the political power of Wei.
Strategy 27 : Feign Madness, But Keep Your Balance
Hide behind the cover of madness and do nothing threatening. This disarms your enemy and makes yourself less of a target. Then just wait for the right moment to strike back.
