一成不易

Explanation: Once formed, no change. With the static. " 　　Source: "History of Ming Li Zhi a" husband-day trip to degrees in many hands and people of limited intelligence ... ... but the thought of people past and present together, heel upgrading things, perhaps that line. It can become difficult for the law also. " 　　Examples: As mentioned silk industry, before the invention of the production and manufacturing methods are good, but ~, the total improvement do not know. ★ Sun "Livelihood" Fourth Lecture