Energy return on energy invested

Eventually, the civilization hit a period of stagflation, typically lasting 50 or 60 years, as the population hit the carrying capacity of the land, and as additional workers did not add proportionately more output. When this happened, the wages of common workers tended to stagnate or decrease, resulting in increased wage disparity. The price of food tended to spike. To counter these problems, the amount of government services rose, as did the amount of debt.

~ Gail Tverberg