萬物流轉，而經之所以為經，乃因其間有恆常的價值原則；史家視史，亦復如是。在時間的波光中，起落翻騰多少人事物，總有些什麼是應該被銘記的。經或史的「褒貶」為的就是披沙揀金，要在人世洪爐中，煉出值得執守的「價值」金丹。 「褒貶」為的是論定是非，宣導價值以垂誡後人，卻也不能不瞻顧其間的曲折，深體當事人進退之間或有的衝突困境；因此，不見全貌的褒貶失之偏頗；抓住來龍去脈後，褒貶就未必能率爾輕出，恐怕也不易以一二字判然分列黑白。 本文以《左傳》對「忠」這個價值的論述作檢樣，一以探求《左傳》如何看待禮樂制度逐漸崩壞時期的君臣關係；二以「晏子不死君難」相關記事呈現《左傳》辯證價值的手法。研究發現《左傳》以「社稷為主」的民本觀念為封建君臣「隸屬」關係解套，對忠或不忠的評判，就容易回歸「任事態度」的檢驗，而非「服事一人」的行為約束。至於褒貶，除了「君子曰」等直接的議論，《左傳》亦巧用敘事結構，達到價值傳遞的企圖，其手法宛如電影導演運動鏡頭，時而拉大視野，讓讀者對是非曲直多一些評判材料；又適時地拉近鏡頭，以特寫的方式，掀開蒙蔽，隱曲幽微的心事得以被窺見，讓讀者在建構價值評斷時多幾個參考座標。總之，務求「原始要終，尋其枝葉，而究其所窮」，在詳盡的背景、不同的角度下，辯證事件的是非曲折，從而建構價值的豐富內涵。

It's the constant values inside the Classics that make them last forever while myriad things changed. The criticisms in the Classics or histories are written to distinguish right and wrong therefore to defend the values that are worth holding. Actually it has no alternatives but to manage the causes and effects or to find why principals get in a dilemma before criticized them. It will be biased if criticisms are restricted to a narrow confine. On the other hand, it's never easy to make criticisms even if we could grasp the whole amount. There are two objects in this essay. First, what exactly loyalty means in "Zuo Zhuan" in such a ethics crunch time. Next, how does "Zuo Zhuan" deal with loyalty which has been blurred with fatuous princes and treacherous ministers. This essay examines arguments about loyalty in "Zuo Zhuan" then find out it's not princes or masters but the country which ministers should be faithful to, that's what called loyalty in "Zuo Zhuan". Also this essay inspects narratives about "Yan Ying didn't die for his prince" to see how critic isms are made in "Zuo Zhuan". As mentioned to how criticisms are made, except "gentlemen said" as usual, there are still other ways. Narrative patterns in "Zuo Zhuan" and lens in a movie are somewhat alike. Audiences or readers will have wider view and get more information while lens zoom out, on the other hand, they can examine events minutely therefore some concealed truth will be unveiled while lens zoom in. In other words, "Zuo Zhuan" tries to show the most processes of events to let readers get more viewpoints and thus construct criticisms by themselves. In this adroit skill in narrative, "Zuo Zhuan" affects readers' judgements and defines values clearly and delicately.