David Brooks lists "concepts worth using in everyday life":

Clay Shirkey nominates the Pareto Principle. We have the idea in our heads that most distributions fall along a bell curve (most people are in the middle). But this is not how the world is organized in sphere after sphere. The top 1 percent of the population control 35 percent of the wealth. The top two percent of Twitter users send 60 percent of the messages. The top 20 percent of workers in any company will produce a disproportionate share of the value. Shirkey points out that these distributions are regarded as anomalies. They are not.