Famously preserved in the chengyu
户限为穿 (hùxiàn wéi chuān, 'the threshold is worn through'). Tang historian Li Chuo records that calligrapher Zhi Yong
智永 became so famous that visitors seeking his work wore down his doorstep, forcing him to clad it in iron — 'iron threshold'
铁门限 (tiěménxiàn) entered the language as a result.
