Book excerpt: For centuries, oligarchs were viewed as empowered by wealth, an idea muddled by elite theory early in the twentieth century. The common thread for oligarchs across history is that wealth defines them, empowers them and inherently exposes them to threats. The existential motive of all oligarchs is wealth defense. How they respond varies with the threats they confront, including how directly involved they are in supplying the coercion underlying all property claims and whether they act separately or collectively. These variations yield four types of oligarchy: warring, ruling, sultanistic and civil. Moreover, the rule of law problem in many societies is a matter of taming oligarchs. Cases studied in this book include the United States, ancient Athens and Rome, Indonesia, the Philippines, Singapore, medieval Venice and Siena, mafia commissions in the United States and Italy, feuding Appalachian families and early chiefs cum oligarchs dating from 2300 BCE.