As a  proverb goes: "Past experiences, guide for the future." When men of noble character rule the country, they study the historical lessons of ancient times, and test them in the present society, especially in managing human relations. They discern the reasons for ancient countries' prosperity or decline, examine the current situation and choose the best opportunity to advance or to retreat. All changes are done orderly and timely.  Therefore because of the persistence in these proper ways of governing, the country becomes peaceful and the people enjoy life.