The original intention is to constantly ponder over the stone and finally turn it into mud, which means unremitting efforts.

The allusion is about Mr. Qi Baishi.

Qi Baishi especially loved seal cutting when he was young, but he was always dissatisfied with his seal cutting skills. He humbly asked an old seal engraver for advice, and the old seal engraver said to him, "Go and pick a cornerstone and go home. Grind it, grind it, and when this stone turns into mud, your seal will be engraved. "

So Qi Baishi did as suggested by the old seal engraver. He picked a cornerstone, carved it and ground it. Compared with ancient seal cutting works, it was carved day and night. Carve, smooth and carve again. I don't know how many blood bubbles have formed on my hands. Day after day, year after year, there are fewer and fewer cornerstones, but the soil deposited on the ground is getting thicker and thicker. Finally, a CHA Ki-seok finally "turned stone into mud".