Robert H. Lieberman said this quote

“ . . . the authors had developed indices that could be employed to measure the state of a civilization, to determine if society was healthy, in decline, or perhaps even dead. The indicators keyed in on everything from the accumulation of refuse to declines in everyday civility. They looked at how a society treated its most vulnerable citizens; examined a culture's architecture, gauging its scale in relation to humans and the surrounding natural world. One of the primary indicators, however, was a measure of the ability of a society's citizens to listen to each other and truly hear what was being said. It evaluated by gradations the ability of individuals to stand motionless for prolonged periods, receptive to their surroundings. ”