What do you mean by blinking?

Describe how time flies, like a white horse passing through a tiny gap.

The original meaning of "fleeting" is like a white horse flying through a gap, which means that time passes quickly and time is fleeting; Can act as an object in a sentence. Idioms come from life between heaven and earth. If it's a blink of an eye, it's just a sudden.

Later generations summed up the idiom "fleeting".

Like a little white horse running in front of a small gap. Describe how time flies. A fleeting moment is a metaphor for how time flies and how time flies.