One winter in the Eastern Jin Dynasty, the north wind roared, the weather was cold and there was heavy snow. Prime Minister Xie An took his nephew Xie Lang and niece Xie Daowen to enjoy the snow. Xie An suddenly wanted to test the children's talents. He pointed to the snowflakes flying in the air, which inspired Xie An's poetic interest. He blurted out, "What is snow like?" Hearing this, several nephews and nieces know that their uncle has come to test them again, and they are all trying to show their poetic talents. My nephew Xie Lang answered first: "There is a difference between sprinkling salt and sprinkling air." Xie An frowned: "The metaphor is not appropriate. You can have such great strength to sprinkle salt all over the sky. Moreover, salt falls straight in the air quickly, not at all like snowflakes. " My niece Xie Daowen shook her head when she heard this. She said unhurriedly, "Catkin didn't fall because of the wind." Xie An nodded and praised again and again, saying, "What a good match! Good match! The wind blows the catkins on the clouds like snowflakes flying all over the sky. Flocculation is as white as snow, and snow is as light as floc. This metaphor is apt and vivid.