James Conca, Forbes: The growing disparity of wealth today has many parallels with the unequal societies that emerged in the Middle Ages, where wealth and power resided primarily in the hands of a few feudal lords. But wealth inequality is not the same as energy inequality. And that is the primary difference between economic inequality in present-day America and Medieval Europe. Wealth inequality is still about a factor of a million, but energy inequality is down to a factor of about ten. That is because energy has never been so cheap and plentiful in the history of humankind as it is today.