What does it mean to look for him in a dream and suddenly look back at that person in the dim light? Any allusions?

I looked for her a thousand times, but I couldn't find her. Turning around, I saw her standing in the scattered light.

Source: Jade Case Yuan by Song Dynasty poet Xin Qiji.

Original text:

Thousands of trees are blooming and stars are everywhere in the east night. BMW carved cars are full of incense. Phoenix flute moves, jade pot turns, fish dragon dances all night.

Moths, snow, willows, gold thread, laughter and incense are all gone. Looking for him in the crowd, suddenly looking back, the man was there, dimly lit.

Vernacular translation:

At night, the east wind blows the Lantern Festival lanterns like thousands of trees, making the fireworks look like falling meteors. Gorgeous carriage fragrance permeates the road. The music played by the phoenix flute fluttered in the crowd, interwoven with the flowing moonlight. All night, fish dragons and lanterns flew one after another. The beautiful women wore bright ornaments and colorful clothes on their heads and swayed in the crowd. They smiled and walked by with a faint fragrance. I looked for her a thousand times, but I couldn't find her. Turning around, I saw her standing in the scattered light.

The word "Yan Xi" starts from the colorful and lively scene of the Lantern Festival, which embodies a female image that is aloof and indifferent, superior and unconventional, and different from the golden jade powder. It entrusted the lonely and noble character of the author who was unwilling to go along with the secular after political frustration. The whole poem adopts the method of contrast. The first one is about the grand occasion of the Lantern Festival, full of dazzling lanterns and loud music. The next part deliberately describes the hero looking for a lonely and tall woman standing in the scattered light among the good women. Delicate conception, delicate language, implicit euphemism and endless aftertaste.

This word was written by a poet who had just defected from the north to the Southern Song Dynasty in Lin 'an, the capital of the Southern Song Dynasty, in Song and Yuan Dynasties or two. At that time, the strong enemy was under pressure and the national situation declined. However, the ruling class in the Southern Song Dynasty did not think about recovery, but was partial to Jiang Zuo and indulged in singing and dancing to whitewash peace. Xin Qiji, who has an insight into the current situation, wants to make up for the sky, but he hates being able to ask for more happiness. He is full of passion, sadness and resentment, interwoven into this picture of looking for Yuan.

Refer to Baidu Encyclopedia-Jade Case Yuan