儒家思想十分看重親族間的倫理，而「親親之道」則是其中的一個討論重點。在過往在對「親親之道」的討論中，多將焦點放在父子，而較忽略兄弟關係，材料則多以《論語》、《孟子》為主。本文透過對比《春秋》三傳及宋代程頤以下諸多理學家對季友的討論，以詮解《春秋》的視角，一方面對此問題提出更多的討論，另一方面也希望豐富《春秋》學的內容。本文分別從：文獻記錄、對季友的評價、《春秋》解經方法反省檢討及對「親親之道」的內容及態度四個方向，仔細探查《春秋》三傳（尤其是《左傳》及《公羊傳》）及宋代程頤、謝湜、胡安國、高閌、朱熹及張洽等人的看法。透過眾人論述對於此事過程及評價的轉變，更了解歷史中儒者的相關主張。

There are many historical events recorded in the Chunqiu 春秋 that were criticized by later Confucians from an ethical perspective. One event that drew the attention of many later Confucian commentators was the conduct of Ji You 魯季友 towards his brothers. Discussions of Ji You’s fraternal behavior figure prominently in the Han era Gongyang zhuan 公羊傳 as well as in Song dynasty Neo-Confucian (lixue 理學) thought. Through a detailed study of the textual record, this study compares and contrasts the assessments of Ji You advanced in the three main commentaries on the Chunqiu and Neo-Confucianism. It aims to shed light on their different attitudes towards “loving one’s relatives” (qinqin 親親), and also the larger transformations in Confucian thought over this period.