Cheap abundant energy

That is, and has been, the foundation of civilization. Without this precious resource we humans are shackled to the daily routine of securing food and shelter for ourselves.

Since the advent of the industrial revolution, when coal became the foundation for development, we have been sailing along with a powerhouse in the hold, getting us where we wanted to go at our whim.

But great civilizations have existed in the past. How did they do it?
Sadly, to a great extent, this was accomplished on the back of slaves, captured in war and/or raised in captivity. That goes for the Greeks, Romans, and many others across the world. And it includes North America before the American Civil war.

Slaves provided that cheap abundant energy and were considered tradable assets by their owners.

Like it or not, in practice, we still do, and are, where debt is used instead of chains.