Fortress Besieged was a long novel written by Qian Zhongshu. It mainly described the contradictions and struggles of an intellectual in a besieged city. The last sentence referred to the relationship problem between Fang Hongjian and Sun Roujia. The meaning of this sentence was that the relationship problem between two people was like a besieged city. The people inside wanted to go out, and the people outside wanted to come in, but they couldn't break through the siege and truly obtain freedom. These words expressed the conflict and struggle between Fang Hongjian and Sun Roujia. Fang Hongjian felt that Sun Roujia wasn't suitable for him, but he couldn't refuse her feelings. Similarly, Sun Roujia also felt that Fang Hongjian wasn't suitable for her, but she couldn't leave him. Neither of them could break through the siege and truly obtain freedom. This sentence also hinted at the complexity and contradiction of human nature. In the process of pursuing love and freedom, people often encountered various difficulties and challenges, which required constant thinking and exploration.