William J. Bernstein, The Birth of Plenty: How the Prosperity of the Modern World Was Created (2004), 3-4.
When we look at the [facts], it becomes crystal clear that something happened … in the early nineteenth century. … [Up] until approximately 1820, per capita world economic growth [the single best way of measuring human material progress] registered near zero. … Then, not long after 1820, prosperity began flowing in an ever-increasing torrent; with each successive generation, the life of the [child] became observably more comfortable, informed, and predictable than that of the father.
Kip on Character 