History and Economics

"The experience of the past leaves little doubt that every economic system must sooner or later rely upon some form of profit motive to stir individuals and groups to productivity. Substitutes like slavery, police supervision, or ideological enthusiaism prove too unproductive, too expensive, or too transient. Normally and generally men are judged by their ability to produce-except in war, when they are ranked according to their ability to destroy.
Since practical ability differs from person to person, the majority of such abilities, in nearly all societies, is gathered in a minority of men. The concentration of wealth is a natural result of this concentration of ability, and regularly recurs in history. The rate of concentration varies (other factors being equal) with the economic freedom permitted by morals and the laws. Despotism may for a time retard the concentration; democracy, allowing the most liberty, accelerates it. The relative equality of Americans before 1776 has been overwhelmed by a thousand forms of physical, mental, and economic differentiation, so that the gap between the wealthiest and the poorest is now greater than at any time since Imperial plutocratic Rome. In progressive societies the concentration may reach a point where the strength of number in the poor rivals the strength of ability in the rich; then the unstable equilibrium generates a critical situation, which history has diversely met by legislation redistributing wealth or by revolution distributing poverty." - Will and Ariel Durant The Lessons of History.