I've been to war, and it's not easy to kill. It's bloody and messy and totally horrifying, and the consequences are serious.

Just after World War II, this country led the world in science by every way you could measure it, yet the number of scientists was a tiny proportion of what it is now.

As you may recall, Truman was extremely unpopular when he finally left Washington in 1953, thanks largely to the Korean War. Today, however, he is thought to have been a solidly good president, a 'Near Great' even, in the terminology of those surveys of historians they do every now and then.

Making peace, I have found, is much harder than making war.

Al Jazeera aired a new tape of Osama bin Laden. It was the usual stuff, he called Bush evil, the Great Satan, called him a war monger. Basically, the same thing you heard at last night's Democratic debate.

These days, our senses are bombarded with aggression. We are constantly confronted with global images of unending, escalating war and violence.

You might hold an ethical position that it's wrong to lie, but if you have plans for a war in Iraq, and you want to keep them secret for practical reasons - to reduce casualties, perhaps - and someone asks you about those plans, you may need to lie for a 'good' outcome.

Every day it becomes clearer that this was the wrong war at the wrong time.

But does that mean that war and violence are inevitable? I would argue not because we have also evolved this amazingly sophisticated intellect, and we are capable of controlling our innate behavior a lot of the time.

The battle for the mind of Ronald Reagan was like the trench warfare of World War I: never have so many fought so hard for such barren terrain.