某些人、事、物可能在千百年後依然備受重視，活在子子孫孫的記憶之中；某些則否。如果環境變遷，這些人、事、物在後代得到或失去了必要條件的支持，他／它們在子孫所建構的記憶中可能就會產生變化。泰國的披邁寺與高棉的吳哥窟就是典型例證。它們在時間上緊緊相連，都成立於12世紀上半葉；空間上--在西北（今泰國）--在東南（今高棉），均曾是吳哥帝國的重要建築。披邁寺成立時為陪都主寺，是帝國經略遠方、開疆拓土的基地之一。它標誌著一種榮耀，一個帝國擴張史上的里程碑。吳哥窟也是帝國主寺之一，它位在京畿，並且曾為古代高棉人想像中的世界中心。它規模宏大，結構嚴謹，雕刻精細，極一時之盛。 雖然兩座寺廟昔日的地位相距不遠，但在當代高棉人的記憶裡相去甚遠。披邁寺自13-14世紀就因帝國衰弱、版圖萎縮而乏人照料，因此頹圮凋零，直到近年才由泰國當局整修，恢復部分舊觀。它曾是吳哥文明所及的範圍之一，但如今遠在異鄉；而且近代高棉血淚斑斑，百姓自顧不暇，已經沒有心思去追憶它，甚至未曾聽聞過它。而吳哥窟在叢林侵蝕後喜獲重生，得到高棉歷代君王的重視，予以維修，如今煥發著容光，放射千年之前的美感。它還得到官方背書，因此活在每個高棉人的心中。由此可知，記憶會因為時空而變化。為因應當前處境，例如官方為了建立國家認同、凝聚人心、合理化其作為，必須強調某些特定對象；於是某些對象會被放大、強調或誇張，某些則可能被忽略甚至遺忘了。

Memory is not fixed, but socially and collectively constructed. The memories of Prasat Hin Phimai (1080-1113, present-day Northeastern Thailand) and Angkor Wat (1113-c.1150, present-day Siem Reap province, Cambodia) by Cambodians can be typical examples. Established in the first half of the 12th century, the two temples were both cardinal state temples of the Angkorian Empire, and enjoyed similar status. However, they have been remembered differently by modern Cambodians. Once an important part of the Angkorian civilization, Prasat Hin Phimai, now a part of Thailand, has been almost forgotten in modern Cambodian history. By contrast, abandoned in 1431, Angkor Wat is still in Cambodia, regarded as a symbol of the Angkorian civilization, employed to strengthen the legitimacy of the governors, and therefore receiving resources for repairing and redecorating constantly. Moreover, Angkor Wat has been employed by the government to encourage and inspire common people, and it has been enshrined in the collective memory of Cambodians. In this case, clearly, the past is constructed selectively (maybe reluctantly) in the light of the present. In the construction, some parts are exaggerated, others, lost and foregotten.