a city has to remain ...open not only to aliens, but as a place for hospitality in the future ...it's not simply the physical occupation of space ...openness has to do with a dimension of symbolic, linguistic possibilities ...The city I would like to live in is a city I could easily leave ...That's why I insisted on the principle of leaving the openness of the city.
(Jacques Derrida, in Derrida, Forster, and Wenders, "The Berlin City Forum Symposium", pp 45, 50, 51.)