Those upper classes, to rule, needed to make concessions to the middle class, without damage to their own wealth or power, at the expense of slaves, Indians, and poor whites. This bought loyalty. And to bind that loyalty with something more powerful even than material advantage, the ruling group found, in the 1760s and 1770s, a wonderfully useful device. That device was the language of liberty and equality, which could unite just enough whites to fight a Revolution against England, without ending either slavery or inequality.