From the idiom "as few as the morning star", it is described as extremely rare, rare and precious.

The idiom "as few as the morning star" was first seen in Xie Tiao's "Lu Jing travels at night": "The morning star is rare, and the morning light is reflected again." Later, Han Yu, a great scholar in the Tang Dynasty, wrote in the poem "Huashan Women Generals": "The Taoist priest in yellow clothes also said that seats are as rare as stars."