Cao Cao often praised Xun You and once said, "Gongda is intelligent but appears foolish; he is courageous but appears cowardly; he is resilient but appears weak. He neither flaunts his talents nor brags about his achievements. You may be as intelligent as him, but you can't pretend to be foolish as well as he does. Even Master Yan and Ning Wu cannot be compared to him." When Cao Pi was still Cao Cao's heir apparent, his father told him, "Xun Gongda is a role model for people. You should treat him courteously and respectfully." When Xun You was ill, Cao Pi visited him and knelt down beside his bed; such was Cao Pi's level of respect for Xun You. Zhong Yao also once said, "Every time I plan something, I'll carefully think through it again and again until I'm certain that I can't make any more changes. However, after consulting Gongda, he always has new insights to offer." Xun You created 12 strategies for Zhong Yao. Zhong Yao died before he managed to finish writing a book about the 12 strategies, hence some of them were lost. The historian Pei Songzhi thought it was a huge pity that Xun You's strategies were lost because Zhong Yao died at the age of 79 – some 16 years after Xun You's death – so he probably should have had ample time to finish writing the book.