In the Warring States Period, there was a man named Zhao Kuo (290 BC-260BC). He loved reading military science books and discussing strategy. When it came to warfare, he could speak and analyze so well that even his father, an experienced general, could not defeat him on the topic. However, he lacked practical experience.
When the State of Qin attacked the State of Zhao, the ruler of the latter believed a false rumor, and replaced the experienced general Lian Po with Zhao Kuo. Inevitably, he was defeated and lost his life since he never fought in a warfare. Soon after, the State of Zhao was destroyed by the State of Qin.
Later, this idiom, “纸上谈兵 (zhǐ shàng tán bīng” came into being, meaning that those who are good at discussing war stratagems on paper are only good at theorizing, but lack practical experience. It also signifies that empty talk can’t become reality.