孔子《春秋經》記魯隱公元年（西元前七二二年）至魯哀公十四年（西元前四八 一年），計二百四十二年間之史事，為中國第一部明確記載年月日之史籍，誠有極寶貴之貢 獻。唯《春秋經》只載綱目，孔子依當時環境背景下之社會倫理標準，寓寄其微言大義，有 其特定之書法與義例，若據其書法筆削來判別事件之是非，未必完全符合歷史事件之真相。 《襄公廿五年春秋經》載云：「齊崔杼弒其君光」。孔子對於弒君事件之書法，《左傳》認 為：「凡弒君稱君，君無道也；稱臣，臣之罪也。」意指不書弒君者之名，唯稱國人弒君， 必是人君無道，舉國欲去之，則罪在人君不在大臣，故不書其名；反之，若書弒君者之名， 則罪在人臣，故書其名以彰其弒君之罪。就此書法觀之，是孔子認為崔杼弒君有罪，故書出 「崔杼」之名。根據《左傳》之記載，發現崔杼所以弒其君齊莊公，係因莊公私通崔杼妻棠 姜，且明目張膽，毫無忌諱，令崔杼十分難堪，是以憤而謀弒。由此客觀事實可知，齊莊公 淫亂在先，被弒實咎由自取也！「崔杼弒其君」實有「是可忍也，孰不可忍」之苦衷。 本文旨在根據《左傳》，探索崔杼弒君之原因與過程，以釐清此歷史事件之真相，並藉此說 明《左傳》之解經特色及其價值。

　　　　　CHUN QIU HISTORY BOOK recorded: CHI country's courtier CHUI ZU murdered his monarch KUNG. Confucius recorded the event that the courtier CHUI ZU murdered monarch KUNG in CHUN QIU HISTORY BOOK. Confucius had the recording rule in the book about murdered matter. His record rule was: When courtier murdered monarch, if it was fault by monarch, he should wrote the monarch's name. If it was the courtier's guilty, he should wrote the courtier's name. When monarch was murdered by courtier, Confucius didn't write the murder's name, It means: the monarch was killed by all people. he was a bad monarch. On the other hand, if Confucius wrote the murder's name, it means: it was the courtier's guilty. He wanted everybody knew who killed the monarch. According to the record regulation, CHUI ZU's name was written in the book, maybe Confucius thought that CHUI ZU had guilty. But when we studied ZUO'S Commentary, we could find the reason why CHUI ZUI killed the monarch. The reason was: monarch was promiscuous with CHUI ZU wife, many people knew the ugly thing. This matter let CHUI ZU feel embarrassed and difficult. CHUI ZU was angry. He murdered the monarch at last. In fact, Chi's monarch was promiscuous. His behavior was incorrect. The result was that he was murdered. CHUI ZU killed his monarch KUNG. This matter had happened that had its background. CHUI ZU couldn't endure monarch KUNG's inapt behavior. The proposal of this paragraph was that based on ZUO's Commentary and other historical books to clarify the history event. To research the real reason and progress for this murdered event. We can find some different meaning between CHUN QIU HISTORY BOOK and ZUO'S Commentary.