The famous phrase "An old horse crouches, aiming at a thousand miles" comes from Cao Cao's work "Although a turtle lives a long life-Step out of the Summer Gate". The "horse" in Crouching Tiger is actually a horse. Cao Cao was 53 years old when he wrote The Life of a Turtle. He said that an old horse also has the lofty sentiments of galloping thousands of miles, and he still has great ambitions in his later years. This poem is impassioned, expressing Cao Cao's views on life and career, and the image of a hero in the world is vividly on the paper. In fact, Cao Cao's greatest achievement in the field of literature is to create the style of Jian 'an literature, which enables Jian 'an literature to flourish in the long-term war-torn social environment. Cao Cao's poems did not copy the meter of Han Yuefu. Although the words are not gorgeous enough, they are sincere and passionate and have high literary value. In addition, it was in the shadow of Cao Cao that the seven sons of Jian 'an made amazing achievements. In the history of literature, people called Cao Cao and his two sons, Cao Pi and Cao Zhi, "Three Caos".