至当不易

Explanation: Extremely; when appropriate; easy to change. Described as extremely appropriate, can not be changed. 　　Source: Ming Li Zhi "burn books read to write the history of Ming emperor Shen Han tube for the Six Secret Teachings," which claims it sink in more long-Ru Shi Renyi For suits, in terms of six to refer to those who, on 'Bo and few to , and less labor power 'takes the character, can be described as to when the irrefutable conclusion. "