What does Ersi Cuilengshan mean?

Describe the feeling of cool autumn night.

1. Two and four refer to the night in the poem, meaning late night or early morning. Cuileng Mountain refers to the color and cool feeling of the mountain.

2. Ersi Cui Lengshan is a poem from "The Autumn Night Will Come Out of the Fence Gate to Welcome the Coolness" by Du Mu, a poet of the Tang Dynasty.