About Zhuge Liang's lines about "Watching the World at Night", be more complete.

Zhuge Liang observed the sky at night and knew that there was dancing, so he borrowed arrows from thatched boats, and he knew that there was wind and offered sacrifices to the east wind. This is all scientifically justified. However, observing the sky, he knew that Cao Cao did not deserve to die, so he sent Guan Yu to release Huarong. Tao, knowing the stars by sight, Pang Shiyuan is dead, these are a bit like the astronomy and geography in the Chinese tradition, the Five Elements and Bagua, and Qimen Dunjia are all simple sciences, which are mixed science and superstition. From a scientific point of view, Kong Ming should be able to predict the weather. It is unlikely to be an accidental factor because Zhuge Liang was confident that there would be an east wind that night. Based on what he learned in Longzhong, Zhuge Liang judged the Bagua and the twelve solar terms through his erudition, as well as the climate in Jiangdong and the climate along the river plus his personal judgment. It was concluded that there would be easterly winds in November. Because if it is winter, the weather changes regularly. After the weather is warm for a period of time, it will rain, then the northwest wind will blow, then the weather will be sunny and cold, and then gradually warmer. At this time, the northwest wind is likely to blow. Zhuge Liang guessed it based on this rule. Zhuge Liang ordered Guan Gong to capture Cao Cao on Huarong Road, but Guan Gong released Cao Cao. Even Liu Bei saw it and asked Zhuge Liang: Why did he send Guan Gong when he knew that he had an old relationship with Cao Cao? Zhuge Liang said clearly: "Looking at the sky at night, Cao Cao's fate should not be decided, so he sent Guan Gong as a favor and let Cao Cao go." Liu Bei had no choice. Now we all know: celestial phenomena have nothing to do with people. This is Zhuge Liang deceiving Liu Bei. Why did Zhuge Liang lie to Liu Bei? Why did he let Cao Cao go? According to the situation at that time, only a three-legged confrontation is more stable. If Cao Cao was captured and killed at that time, and Liu Bei's foundation was not stable at that time, Sun Quan would definitely send troops to take control of Xuchang, and the power would be great. Liu Bei had no land and no city, so he was bound to be captured by Sun Quan soon. Therefore, if he let Cao Cao go, Liu Bei still had a way out. If he killed him, he would not be able to protect himself. According to the novel, Liu Bei only had Jiangxia County at the time, which was a small place. How could he compete with him? Strong enemy to contend with! However, Cao Cao's 830,000-strong army was wiped out in ashes, his strength was greatly damaged, and he was unable to move south again. At that time, Zhuge Liang wanted to divide the world into three parts, and Soochow (Lu Su in history also proposed to divide the world into three parts) also wanted to stand as a tripartite. Therefore, the three kingdoms must stand in a tripartite position so that Liu Bei can have a foothold and realize the ideal of "restoring the Han Dynasty" . If Cao Cao is killed, the northern Cao Wei group will be leaderless, and Sun Quan's morale is strong at that time. So as long as Sun Quan goes north to attack Cao Wei, it will definitely be easy. Then Liu Bei's three points of the world will be in vain, and his own life will not be saved. Therefore, Zhuge Liang arranged this for the sake of Liu Bei's future. If Guan Yu had not guarded the Huarong Road, but Zhang Fei and Zhao Yun had guarded it, Cao Cao would have been doomed. After Cao Cao's death, the north was in chaos, and the north would return to a situation where heroes were competing for hegemony. At this time, Sun Quan might indeed attack the Central Plains northward. If Sun Quan invades the Central Plains and captures Xudu, then Sun Quan will choose whether to support Emperor Xian of Han or to abolish Emperor Xian of Han. I think Sun Quan is most likely to choose the former. If he abolishes Emperor Xian of Han, he will become another Dong Zhuo. It will even become the public enemy of other forces. Besides, if Sun Quan marches straight into the Central Plains, won't he be afraid that other forces will unite to deal with him? Aren't you afraid that Jiangxia's Liu Bei will stab him in the back? Therefore, the possibility of Sun Quan's Northern Expedition is unlikely.