禀性难移
  1. It's easy to change rivers and mountains but hard to change a person's nature; a fox may grow grey,but never good; a sow,when washed,returns to the muck; it is hard to change man's natural disposition than to change rivers and mountains
    　　Explanation: Nature difficult to change.
    　　Source: Yuan Shang Zhongxian "Dongting Liu Yi Shu" Wedge: "No gratitude, to his first, spots. Noda my shortness Canhong the years, from the Feng Ge near fishing Angeles.