in his masterpiece on the philosophy of history, the Muqaddima, Ibn Khaldun wrote of orange trees as a sign of social decadence: ‘This is the meaning of the statement by certain knowing people, that if orange trees are much grown in a town, the town invites its own ruin.’ Not, Ibn Khaldun hastened to add, that orange trees are a bad omen or anything like that, but they are, like cypress trees, a sign of a sedentary culture. Such trees produce no edible fruit, but are planted only for the sake of their appearance.