We've spoken of borderlands, and how they are both linked and divided. Here is a border sea, differing in many ways but sharing the basic characteristic of the borderland. Proximity separates as much as it divides. It facilitates trade, but also war. For Europe this is another frontier both familiar and profoundly alien. Islam invaded Europe twice from the Mediterranean — first in Iberia, the second time in southeastern Europe, as well as nibbling at Sicily and elsewhere. Christianity invaded Islam multiple times, the first time in the Crusades and in the battle to expel the Muslims from Iberia. Then...
