It tells the story of a little sparrow and his father. The drift bottle here is because the little sparrow likes to put some by the river when he is worried. The drift bottle leaves his own little secret there and lets it drift away. When he grows up, the little sparrow becomes an orphan. The little sparrow has been a child without a mother since he was born until he can remember. There is no trace of his mother in the little sparrow's memory, and he even has no way of knowing what she looks like.
Purpose: Bring these things to more people and let them think about the past