Journey to Portugal by José Saramago

Nothing of the kind had occurred within the living memory of any border guard. This was the first traveller ever to pull up in his car, with the engine already in Portugal but the petrol tank still in Spain, and lean over the parapet at the precise point crossed by the invisible line of the frontier. Then, from across the deep dark waters, echoing between the tall rocky slopes on either side, the traveller's voice could be heard preaching to the fish in the river: 1

"Gather round, fishes, those of you to the right still in the River Douro and those of you to the left in the River Duero, come closer all of you and advise me which language you speak when you cross the watery frontiers beneath, and whether down there you also produce passports and visas as you enter and depart. Here am I, gazing down on you from this high barrier, as you gaze back up at me, fishes residing in these mingling waters, and who can as easily find yourselves on one shoreline as on another, a grand fraternity of fishes who only devour one another for reasons of hunger and never on a patriotic impulse.