"The Ottoman Empire was, of course, much more than a military machine. A conquering elite (like the Manchus in China), the Ottomans had established a unity of official faith, culture, and language over an area greater than the Roman Empire, and over vast numbers of subject peoples. For centuries before 1500 the world of Islam had been culturally and technologically ahead of Europe. Its cities were large, well-lit, and drained, and some of them possessed universities and libraries and stunningly beautiful mosques. In mathematics, cartography, medicine, and many other aspects of science and industry—in mills, gun-casting, lighthouses, horsebreeding—the Muslims had enjoyed a lead. The Ottoman system of recruiting future janissaries from Christian youth in the Balkans had produced a dedicated, uniform corps of troops. Tolerance of other races had brought many a talented Greek, Jew, and Gentile into the sultan’s service—a Hungarian was Mehmet’s chief gun-caster in the Siege of Constantinople. Under a successful leader like Suleiman I, a strong bureaucracy supervised fourteen million subjects—this at a time when Spain had five million and England a mere two and a half million inhabitants. Constantinople in its heyday was bigger than any European city, possessing over 500,000 inhabitants in 1600."