From "The Collection of Zhuge Liang, Volume 3, Sixteen Cheap Strategies, Joy and Wrath Eleven"

The policy of joy and anger means that you should not be happy when you are happy, and you should not be angry when you are angry. A thing without anger must know its kind between joy and anger. Those who are angry will not offend those who are innocent, and those who are happy but will not follow can be killed. When you are happy or angry, you must not be ignorant. Do not indulge in guilt when you are happy, do not kill innocent people when you are angry, and do not act rashly when you are happy or angry. If you pursue your own interests and neglect your merits, you will not be able to express your personal anger. If you want to start a war, you must use the hearts of the masses. If you refuse to cooperate and fight together because of your private anger, you will be defeated if you use the hearts of the masses. Anger cannot be restored to joy, joy cannot be restored to anger, so literature comes first and martial arts comes second. If you win first, you will lose later. If you are angry first, you will regret it. Once you are angry, you will die. Therefore, a gentleman is mighty but not fierce, angry but not angry, worried but not afraid, happy but not happy. If something is outrageous, then add force. If force is added, punishment will be given. If punishment is given, the traitors will be blocked. If there is no force, the punishment will not be accurate. If the punishment is not accurate, the evil will be ignored and the country will perish.

The famous saying is said to be attributed to Chen Shou, probably because "The Collection of Zhuge Liang" was edited by Chen Shou.