What artistic techniques are used in the first and second sentences of Shouxiang's "Listening to the Flute on the Wall at Night", what kind of scenes are described and what is the role?

The first and second sentences of Shouxiang's poem "Listening to the flute on the wall at night" use figurative rhetoric to describe the scene that the sand is as white as snow in front of the back peak and the moonlight outside the city is like autumn frost, which plays a role in setting off the environment at that time.

Night Cry at the Watching Wall is a seven-character quatrain written by Li Yi, a poet in the Tang Dynasty. Full text: The sand is like snow before Yuefeng, and the moon outside the city is like frost. ? I don't know where the bleak reed flute blows and I look at my hometown all night.

Before returning to Yuefeng, the sand is as white as snow, and the moonlight outside the city is like autumn frost. I don't know where the bleak reed flute blows, and all people look at their hometown overnight.

Full text appreciation:

Judging from the whole poem, the first two sentences are written in color, and the third sentence is written in voice; The last sentence expresses my inner feelings and writes about love. The first three sentences set off and pave the way for the direct lyric of the last sentence. The visual image inspires homesickness at first, and then the auditory image leads the undercurrent of homesickness to the torrent of emotion.

The first three sentences are more ready, and the last sentence is usually written directly. Yi Lee, on the other hand, found another way, making the feeling of full pregnancy make a detour at the end, expressing it with an imaginary lens that people look forward to their hometown, which makes people feel that the sentence is absolutely endless, and it still ripples one after another at an abrupt end.

The artistic success of this poem lies in the integration of scenery, sound and emotion, and the integration of emotional appeal, artistic conception and musical beauty into a complete artistic whole, which has the characteristics of muddy artistic conception, simple and ethereal spirit and endless meaning.