Significance of Tombs to Unknown Soldiers

At the beginning of his captivating history of nationalism and its connections to the popular dissemination of the printed word, Benedict Anderson describes the cultural significance of tombs to Unknown Soldiers. His discussion is just as noteworthy as any other on Memorial Day:

No more arresting emblems of the modern culture of nationalism exist than cenotaphs and tombs of Unknown Soldiers. The public ceremonial reverence accorded these monuments precisely because they are either deliberately empty or no one knows who lies inside them, has no true precedents in earlier times. To feel the force of this modernity one has only to imagine the general reaction to the busy-body who "discovered" the UnKnown Soldier's name or insisted on filling the cenotaph with some real bones. Sacrilege of a strange, contemporary kind! Yet void as these tombs are of identifiable mortal remains or immortal souls, they are nonetheless saturated with ghostly national imaginings. (This is why so many different nations have such tombs without feeling any need to specify the nationality of their absent occupants. What else could they be but Germans, Americans, Argentinians ... ?)

The cultural significance of such monuments becomes clearer if one tries to imagine, say, a Tomb of the Unknown Marxist or a cenotaph for fallen Liberals. Is a sense of absurdity avoidable? The reason is that neither Marxism or Liberalism are much concerned with death and immortality. If the nationalist imagining is so concerned, this suggests a strong affinity with religious imaginings.