We can never achieve physical security by fighting wars or building walls. The War on Poverty, the War on Drugs or a war against any disease, cannot succeed. All the wars that have been fought throughout history — even those fought for what we might call “good reasons” — all these wars have not created a secure world. Walls may keep danger out, at least for awhile, but they also lock us in. This is true about concrete walls, but it’s also true about mental walls. When our mind is constantly working, trying to anticipate what bad thing might happen next and how can we defend ourselves against it, the one thing we can be sure of is that we’re going to have lots of things happen that we need to defend against.