In 1683 the Ottoman army laid siege to Vienna, the capital of Europe's most powerful empire. Domination of West by East was an alarmingly plausible scenario. But the Ottoman army was defeated: not so much by firepower as by science. Ferguson asks why the Islamic world didn't participate in the Scientific Revolution and the Enlightenment, and if the West is still capable of maintaining its scientific lead at a time when educational attainment in science subjects is declining.