Simmel acknowledges the bridge’s typical function of connecting two otherwise separate and diverse things. However, he prods this understanding a bit further to suggest that the real appeal of the bridge and the connectedness that it provides is that the presence of the bridge underlines the its own necessity. Seeing a bridge calls to mind the division that it bridges, for lack of a better word, while giving the viewer the sense that the two halves are connected. With the bridge, unity or connectedness is always eventually emphasized.
With a door, however, the emphasis falls on the division or differentiation of things rather than their unity. The door embodies both unity and division and is the ultimate expression of the human capability to determine how one’s space is configured. The human decides where to place a door and when to open or close it. The door emphasizes both human isolation (positive and negative) and confrontation with what lies outside the door (both positive and negative, again). The door empowers the human to take control of when the human is isolated.
Nice quote: “The human being who first erected a hut, like the first road-builder, revealed the specifically human capacity over against nature, insofar as he or she cut a portion out of the continuity and infinity of space and arranged this into a particular unity in accordance with a single meaning. A piece of space was thereby brought together and separated from the whole remaining world. By virtue of the fact that the door forms, as it were, a linkage between the space of human beings and everything that remains outside it, it transcends the separation between the inner and the outer. Precisely because it can also be opened, its closure provides the feeling of a stronger isolation against everything outside this space than the mere unstructured wall. The latter is mute, but the door speaks. It is absolutely essential for humanity that it set itself a boundary, but with freedom, that is, in such a way that it can also remove this boundary again, that it can place itself outside it.”
Related: the window does not provide the same satisfaction. The window emphasizes connectivity with the outside world, but is intended solely for looking from the inside out, and NOT the other way around (CONNECTION: think about Appleton – Prospect-Refuge theory… we feel vaguely unsafe in a dark house at night, lights on but curtains open. Why? Because we can’t clearly see what is outside, but the outside can see clearly in.)
Summary quote: “Because the human being is the connecting creature who must always separate and cannot connect without separating – that is why we must first conceive intellectually of the merely indifferent existence of two river banks as something separated in order to connect them by means of a bridge. And the human being is likewise the bordering creature who has no border. The enclosure of his or her domestic being by the door means, to be sure, that they have separated out a piece from the uninterrupted unity of natural being. But just as the formless limitation takes on a shape, its limitedness finds its significance and dignity only in that which the mobility of the door illustrates: in the possibility at any moment of stepping out of this limitation into freedom.