The next sentence of "suddenly looking back" is "that man is there, and the lights are dim." This word comes from the Song Dynasty poet Xin Qiji's Jade Case Yuan Xi, and the whole poem is:

Thousands of trees bloom at night in the East. It blows down and the stars are like rain. BMW carved cars are full of incense. Phoenix flute moves, jade pot turns, fish dragon dances all night.

Moth, snow, willow, golden thread. The laughter faded away. Look for him in the crowd. Suddenly looking back, the man was there, dimly lit.