Why is Liu Ji called legend in history?

Of course, the real Liu Ji in history is not a fairy, but according to today's title, he can be regarded as a philosopher, strategist, writer, military theorist, Yi-ology scholar, astronomer and so on. His works also cover these aspects extensively. "His article is magnificent and strange, just like Song Lian." Li Yu Ion written by him has a strange imagination and profound implications, such as Zhuangzi and Hundred Wars, which is a collection of art books (whether he can do it or not is still controversial by later generations). The astronomical calendar includes The Secret of the Secret, which has been passed down from generation to generation, and an almanac, The Golden Book of Jade Cave. Strangely, unlike the traditional cadets holding feather fans and wearing black scarves, Liu Ji is dressed in cloth and brave and resolute, completely like a Liangshan hero.