1. SOLAR ENERGY & CIVILIZATION:
No terrestrial civilization can sever its dependence on solar energy; its flows sustain the biosphere and power the photosynthetic production of our food.
Traditional societies drew their food, heat, and mechanical power from sources that were almost immediate transformations of solar radiation (flowing water and wind), or harnessed it in the form of accumulated biomass that took
a) a few months (crops harvested from food and fuel),
b) a few years (draft animals, human muscles, shrubs, young trees) or
c) a few decades (mature trees) to become useful.
Modern civilization, however has modified this in that a) it depends on fossilized stores of solar energy extracted as coals and hydrocarbons (petroleum and natural gas), and b) it increasingly relies on electricity, which it generates by burning fossil fuels, harnessing solar radiation (mostly indirectly via water & wind), and utilizing geothermal and nuclear energy.
Thus traditional societies relied on nearly instantaneous and constantly replenished solar income flows, while modern society is withdrawing accumulated solar capital (fossil fuels in the form of stocks) at rates that will exhaust it in a tiny fraction of the time needed to create it.