Blue sky is a Chinese word, pronounced green II, which is called "blue sky" by Taoism, because on the first day of the East, the sky was covered with blue clouds. Here refers to the sky in general.
In the Taoist culture of China, death refers to the place where people go after death, that is, the underworld. Death is also one of the nine prisons and nine springs. There are similar sayings in the cultures of Japan and the Korean Peninsula.
Above, he looked for the green void, below, the yellow spring, but he didn't find the one he was looking for in two places. From Tang Bai Juyi's Song of Eternal Sorrow.
Song of Eternal Sorrow is a long narrative poem by Bai Juyi, a poet in the Tang Dynasty. The whole poem vividly describes the love tragedy between Xuanzong of Tang Dynasty and Yang Guifei. With the help of historical figures and legends, poets have created touching stories and reproduced the truth of real life through their own artistic images, which have infected readers for thousands of years. The theme of this poem is "Song of Eternal Sorrow".
This poem has had a far-reaching influence on many literary works in later generations.