One of the chapters of "Old Stories in the South of the City", "Rolling on a Donkey", mainly tells that Song Ma came to Lin Yingzi's house as a wet nurse because of difficulties in life, and stayed at home because she worked hard. She has been sending a letter of peace to her family and her salary, hoping to make her son Xiao Shuan have a better life. But her husband took the money to gamble, and when he had no money, he asked Song Ma for money, so Lin Yingzi's parents hated him. Later, Song Ma learned that Xiao Shuan died several years ago, and Song Ma was very sad.