The word "Wolf Gu" comes from a description of the living habits of wolves-always look around when walking, and even look back 180 degrees! This skill is very rebellious, and it is estimated that it is second only to owls in the animal kingdom. In addition, due to the ferocious nature of wolves, the ancients feared and hated wolves, so they extended the description of wolves to people. For those who are extremely shrewd and suspicious, it is called "wolves protect each other."

As we all know, Cao Cao was a suspicious person in the troubled times of the Three Kingdoms. When he learned that Sima Yi was a talented young man, he wanted him to be an official. Unexpectedly, Sima Yi is also a scheming person. He immediately said that he was ill, shirked his responsibility and successfully deceived Cao Cao. However, after seven years, Cao Cao still gave Sima Yi the title of "literature". The seemingly insignificant official was the beginning of Sima Yi's official career. Of course, Cao Cao, who was busy with everything, soon forgot the existence of Sima Yi until Cao Cao, who "killed in a dream", had another dream.

According to Xuandi Ji, Cao Cao saw three horses eating in the same trough in his dream. When he woke up, he felt that this was an ominous sign and he was very unhappy. Because Sima Yi and his son are both DPRK officials, Cao Cao has bad feelings. In addition, Cao Cao also heard that someone suddenly called him behind Sima Yi. Sima yi was frightened and suddenly turned back. His movements and eyes are exactly the same as those of a wolf! Sima Yi had concerns about wolves, so it spread.