There has never been a century that has not had a systemic war - a systemic war, meaning when the entire system convulses. From the Seven Years' War in Europe to the Napoleonic Wars of the 19th century to the World Wars, every century has one.

The Chinese have a long history of slaughtering each other without bothering their neighbors.

But every time new powers emerge they have to find their balance. New powers are emerging, old powers are declining. It's not that process that's dangerous, it's the emerging position that's dangerous.

Constraint theory asks: What is the price for doing this? Now one way around constraint theory is declaring your enemy crazy. Crazy and stupid are not concepts used in forecasting. When people say they're really stupid or they're crazy, that's laziness. That means I don't want to think through their position or about what they're really going to do.

War and sex are what I call the two abysmal - by that I mean deep - parts of the human condition.

By the 20th century, war ceased to be an encounter between two armies. It became an encounter between two societies, because a factory worker producing a gun or a bomb is as deadly as a pilot.

Now if you can recognize and memorize a grandmaster's game, and you have the respect to understand [Zimbabwean president Robert] Mugabe who has survived past anyone's expectations, and make the simple assumption it wasn't an accident, and you understand why he did what he did, now you're ready to predict ... The key to forecasting is to understand both the constraints nations are under and the manner in which the struggle for power shapes leaders.