These two sentences came from the poem "Autumn Dusk in the Mountains" by Wang Wei, a poet of the Tang Dynasty. It meant that although the green mountains still existed, the afterglow of the setting sun often shone on the top of the mountain. These two lines of poetry depicted a picture of natural beauty, showing the harmonious co-existence of man and nature. Green Mountain still existed, which meant that things in the natural world were constantly developing and changing, but Green Mountain itself was eternal and unchanged. Sunset Glow referred to the beauty and splendor of the setting sun, expressing the short and impermanence of life. These two lines express the short life and the eternal nature through the description of the natural landscape, reflecting people's love and awe of nature.