Opera and ballet of the highest order, in stunning settings of antiquity, are what we are promised in Turkey’s lavish festivals this summer. An attractive land of mystery, of exotic art and culture, a land ‘full of eastern promise’ was how Turkey—or the Ottoman Empire as it was once known—was perceived in the west for many centuries. To westerners, for example, the instruments used in the country’s ‘marching bands’ entranced our most famous classical composers...