"Although it is hard work after thousands of scourings, only after blowing away all the yellow sand can you find gold" comes from "Lang Tao Sha" by Liu Yuxi, a poet of the Tang Dynasty.

The whole poem is: Don’t say slanderous words are as deep as the waves; don’t say that moving away is like the sinking sand. Although it is hard work to search for thousands of pounds, you can only find gold after blowing away all the yellow sand. "Although it is hard work to search for thousands of pounds, you can only find gold after blowing away all the yellow sand."

Meaning: Gold mining in the sand will only appear after thousands of screenings and filtrations, wind and rain, frost and snow, and countless hardships and blowing away all the sand. Yellow gold. These two poems express that people need to work hard, temper, and try if they want to succeed. They also show that only through hard work and countless hardships can people hone their tough character and noble sentiments.