what he sought was always something lying ahead, and even if it was a matter of the past it was a past that changed gradually as he advanced on his journey, because the traveler’s past changes according to the route he has followed: not the immediate past, that is, to which each day that goes by adds a day, but the more remote past. Arriving at each new city, the traveler finds again a past of his that he did not know he had: the foreignness of what you no longer are or no longer possess lies in wait for you in foreign, unpossessed places. Marco enters a city; he sees someone in a square living a life or an instant that could be his; he could now be in that man’s place, if he had stopped in time, long ago; or if, long ago, at a crossroads, instead of taking one road he had taken the opposite one, and after long wandering he had come to be in the place of that man in that square. By now, from that real or hypothetical past of his, he is excluded; he cannot stop; he must go on to another city, where another of his pasts awaits him, or something perhaps that had been a possible future of his and is now someone else’s present. Futures not achieved are only branches of the past: dead branches.

- Italo Calvino, Invisible Cities