This classic comes from Mencius' chivalrous man: "If you enter, you will not be able to go home; if you leave, you will be invincible against foreign invasion, and your country will perish.". Then I know that I was born in sorrow and died in happiness. "
Mencius, a thinker in the Warring States Period, often educated monarchs in some countries to work hard, encouraged himself and tempered his will in sorrow and suffering. In his view, those who can shoulder the heavy responsibility have experienced arduous tests and tribulations: the legendary Yu Shun was once a farmer, and Fu Shuo of Shang Dynasty was a bricklayer. During the Spring and Autumn Period, Guan Zhong, Sun Shuai, Prissy and others were imprisoned and lived in seclusion by the sea, herding cattle for a living. After these tempering, they all took up important positions and became very successful people.
Mencius pointed out that if a country is always in happiness, there will be no strict law enforcers and ministers who dare to remonstrate, and there will be no worries about enemy attacks, so the country will often perish. In this sense, sadness and pain can make people live, and ease and enjoyment can make people die.