"During most of human history, historical change has not been visible to the people who were involved in it, or even to those enacting it.  Ancient Egypt and Mesopotamia, for example, endured for some four hundred generations with but slight changes in their basic structure. That is six and a half times as long as the entire Christian era, which has only prevailed some sixty generations; it is about eighty times as long as the five generations of the United States' existence. But now the tempo of change is so rapid, and the means of observation so accessible, that the interplay of event and decision seems often to be quite historically visible, if we will only look carefully and from an adequate vantage point" (The Power Elite, 1956, pp. 20-21).