本文討論歷史上東西對立觀念的發展，並檢討此一觀念對於理解與詮釋西洋文化史的作用。作者所欲說明的，是文化觀念下的東西不同於地理分界的東西；這不是要論誰何者為是，而是要指出東方觀點下的「西方」可能不是西方人眼中的西方，反之亦然。傳統「西洋文化史」學科所籠統處理的西方，大致看來並不吻合文化意義上的西方，或是西方人所自覺的西方世界。故此課題能否有效呈現一貫而有獨特性的西洋文化及其歷史發展，甚令人困惑。本文處理希臘以下至今的東西對立觀念之發展，以及文化上東西分界在歷代的變遷情形，尤其強調中古以下拜贊廷、俄羅斯及回教帝國等文化圈對於這個發展與變遷的影響。而第三羅馬 (莫斯科) 與共產蘇聯政權的興起，更使東西對立問題顯得複雄，因而若不能明辨這個問題，則所謂的西洋文化將被視為含混的「非東方」文化，這對吾人對西方的認知，恐無多助益。文末檢討忽略此脈絡而設計的「西洋文化史」，在教與學上所面臨的困難與造成的缺失，最後提出作者的建議以為改善之參考。

This article aims to clarify how the world was and is divided into “East” and “West” in a cultural sense, and thereby to argue that the topic of “Western Civilization” must be treated in the context of cultural differentiation. Generally, the countries that geographically constitute Europe do not match those that make up the cultural conception of the “West”. Therefore it is misleading to talk about Western civilization as being demarcated by the boundaries of Europe. What Easterners regard as “Western” is not necessarily equivalent to what Westerners think they are, and vice versa. The author shows that the line separating the East from the West has changed repeatedly since ancient times, and that the confrontation between the two worlds was aggravated by the challenges posed by Byzantium, Islam, and Tsarist Russia for the European West. The rise of the Third Rome (Moscow) and Communist Russia greatly complicated the conflict between East and West, making it even more important to define Europe from a historical perspective to present Western civilization in an intelligible and coherent way. The article concludes by arguing that the term “Western Civilization” should be confined to the civilization of Western Christendom, and should not include the civilizations of the Slavs or the Muslims. Casually defining “Western Civilization” as the “non-Oriental civilization” is not only mistaken but useless for scholarly research.