No slave system has ever been able to continue to function on the slaves provided by its own biological reproduction because the rate of human reproduction is too slow and the expense from infant mortality and years of unproductive upkeep of the young make this prohibitively expensive. This relationship is one of the basic causes of the American Civil War, and was even more significant in destroying ancient Rome.

It is also in theory, conceivable that some universal empire some day might cover the whole globe, leaving no external "barbarians" to serve as invaders.

The process by which civilization, as an abstract entity distinct from the societies in which it is embodied, dies or is reborn is a very significant one.

It is not easy to tear any event out of the context of the universe in which it occurred without detaching from it some factor that influenced it.

A civilization is complicated, in the first place, because it is dynamic; that is, it is constantly changing in the passage of time, until it has perished.

The difference between a stable society and an unstable one is that the restraints in an unstable one are external. In a stable society government ultimately becomes unnecessary; the restraints on people's actions are internal, they're self-disciplined.

There were people who said the Society of Cincinnati in the American revolution, of which George Washington was one of the shining lights, was a branch of the Illuminati.