This poem describes the scene poem of catkins flying in spring, and also implies the reunion of old people. In the wind, catkins are scattered everywhere. When I was young, old people drifted around with the world. Today, they finally met. It may have been a long time, and almost all of them are passers-by. So I used "pedestrian laugh". It turned out that the old people met. This poem is simple, but it has profound meaning.
The last sentence is a pun. First, the willow tree looks like an old man. Second, it is said that old friends have been reunited for many years, and it is already a dying day.