Where did the moment that should last forever come from?

And a moment that should last forever, this poem comes from Li Shangyin's ancient poem "Jinse".

Jin Se Tang Li Shangyin

I want to know why my Jinse has fifty strings, and each string has a youthful interval.

Zhuangzi daydreaming, a saint, was bewitched by butterflies, and cuckoo crowed in the imperial spring.

Mermaids shed pearl-like tears on the moon-green sea, and the blue fields breathed their jade to the sun.

A moment that should last forever has come and gone before I know it.

There is no reason to say that Jinse has fifty strings. But even so, every string and syllable of it is enough to express the yearning for that wonderful time. Zhuang Zhou actually knows that he is just a butterfly yearning for freedom. Wang Di's beautiful heart and behavior can move Du Fu. The shadow of the bright moon on the sea turned into tears like pearls. Only then can Lantian in another place produce something as beautiful as smoke. Those beautiful things and years can only stay in memories. At that time, those people thought those things were just ordinary, but they didn't know how to cherish them.