The heraldic image of our century is that of the frontier. Before 1914, my father, then a law-student of very limited means, could travel the length and breadth of Europe with only a card of identity, bearing cursory witness to his academic status. The demand for a passport and visa made by imperial Russia was, in the enlightened west, regarded as eccentrically symptomatic of a retarded, oriental despotism.

Today, the frontier is the dominant fact of international existence. And when we say 'frontier', the image that comes to mind is, unavoidably, one of barriers whose inhibiting brutality, whose enormity in respect of the logic of landscape and of human contacts, have only few precedents in recorded history. Our sense of borders is that of mine-fields and barbed wire, of watch-towers lit in the night and tank-traps. Its ante-chamber is the consular office, the banal inferno of waiting in which the visas, the transit permits, the temporary papers for the stateless and the hunted, are granted or withheld. Very often, in this twentieth century, it has not been high judges or tribunals who have ministered to life and death: it has been bored vice-consuls and frontier-guards.

In its starkest, most systematic guise, the modern territorial-ideological border mocks rational imagining. During the occupation of France in the early 1940s, a wire-fence, padlocked, searchlit and patrolled, separated the French part of the station-platforms at Geneva from the Swiss part. Standing in darkness, those on the French side of ...