The source of allusions

The forty-ninth chapter of Ming Luo Guanzhong's Romance of the Three Kingdoms: "Zhuge Liang took a pen and paper, and the screen retreated to the left and right. The secret book said: If you want to break Tsao Gong, you should attack with fire; Everything is ready, only the east wind. "

The story told in the sixth episode of TV series should be before Battle of Red Cliffs, and Zhuge Liang had not said this at that time.