According to Baidu Encyclopedia, the famous saying that the pestle is ground into a needle means that as long as you work hard, the pestle is ground into a needle. This is a proverb. Metaphor as long as you are determined and willing to work hard, how difficult things can be successfully completed.

Allusion: Li Bai, a famous poet in the Tang Dynasty, never studied hard when he was a child and often threw his books out to play. One day, Li Bai met a white-haired old woman who was grinding a big iron bar on a stone. She was curious and asked what she was doing. The old woman told him to grind it into an embroidery needle. Li Bai was deeply moved, studied hard and finally became a writer.