Master Ai had a grandson about 10 years old. As he was wicked and not eager to learn, his grandfather often gave him a good caning. His father, therefore, was awfully afraid this only son would not survive this frequent caning. So every time Master Ai took his son to task, he would weep and intercede with his father for his son. One snowy day, Maser Ai, having caught his grandson pressing snowballs, made him kneel down in the snow after stripping his coat off.

The boy’s father, seeing that his poor son was shivering with cold and not daring to say a word, took off his own coat and knelt down beside his son. Very much surprised, Master Ai inquired, “Your son is guilty and deserves punishment. But why you…?” “Since you’re freezing my son to death,” replied the father, “I want to freeze yours to death. It’s just tit for tat.” Master Ai was very mush amused at these remarks and let the boy go.