Its background is that when Shen Yifu was eight years old, his teacher ordered the cloud: the green water is leisurely and his face is wrinkled by the wind. Shen Yifu saw that the snow on the distant castle peak had not melted, like a white-haired old man, and suddenly he had a brainwave and said this beautiful word. The significance of this connection: water has nothing to worry about, but it ripples because of the wind, just like people are sad. Castle Peak will never grow old, but covered with snow, it will turn white like a sentimental person.
Whether it is ancient poems or couplets, their charm lies in expressing rich connotations with short sentences. I don't think there is necessarily a unified view on how to appreciate ancient prose. In fact, no matter how much later generations appreciate it, it can't fit the author's real feelings after all, and even the author himself can't feel the same way about his own work.