The story of the origin of solar terms in Grain Rain

The book Huai Nan Zi says that "when it rains, millet will cry at night". In other words, the whole people celebrated the day when Cangjie succeeded in creating characters. God was moved by Cang Xie's noble character and hard work. Millet fell from the sky, just like rain, and even ghosts cried at night. This is also the origin of the season in Grain Rain.