Borders are a very recent invention which has still to be perfected. Spain’s with France and Portugal, supposedly among the world’s oldest, were not marked out until the 19th century, and minor modifications were made even into the 1990s. The ecumenical and enlightened cliché takes them to be legacies of a violent, uncivilized past, but data show that the farther back we go in time, the weaker and vaguer they are. From the comfort zone of Schengen it may look otherwise, but for someone from Mali or Bolivia trying to get into the European Union, borders are a hypertechnological fact, increasingly advanced and oppressive...