In Stalin's Russia racial persecution was often disguised as class warfare. More than 1.5 million members of ethnic minorities died as a result of forced resettlement.

The Japanese Co-Prosperity Zone began as a racist utopia and ended as a cross between an abbatoir, a plantation and a brothel.

All empires have depended on local legitimacy and local collaboration; they are not based primarily on coercion. An imperial rule that relies wholly on coercion can't endure. It's too expensive.

If young men have jobs - or the prospects of jobs - they are less likely to take up arms, they are less likely to join the resistance.

As a teacher, my strategy is to encourage questioning. I'm the least authoritarian professor you'll ever meet.

Empires, essentially, create order. In their absence, you don't end up with lots of happy, little nation-states full of people sitting around campfires singing John Lennon's "Imagine." What you end up with is civil war, anarchy.

The West may collapse very suddenly. Complex civilizations do that, because they operate, most of the time, on the edge of chaos.