The fourth poem: Express the author's determination to strive for self-improvement. 13 paragraph expresses that we should ignore the temptation in front of us (referring to flowers and shade) and work hard for the goal of struggle: 16 paragraph expresses that one day, even if "I" leave Peking University and rely on it, I am still not a boat. I wrote it from the perspective of the text. 16 paragraph focuses more on "I am the will, and the ship that is not tied is me/even without wisdom/rope sail", that is to say, I have no advantages and objective conditions, and I am still a ship that is not tied.