And there will continue to be a specific threat, and there will continue to be terrorism, as there has been for as long as human history exists.

But the irony is they think they're being tough on ISIS and Trump thinks he's being tough on ISIS. Senator Rubio in his interview with you touched on it very, very lightly.

The problem is everybody is worrying about explosive vests and people with AK-47s. We live in a day and age when someone sitting in Somalia or in Chile or in Perth, Australia, can be sitting there with a laptop and can theoretically take down one of our power grids or part of our infrastructure and do infinitely more damage. Nobody talks about that. It's not a question of who comes into the United States. We're way past that.

If we're able to identify our own ignorance, we can identify someone else's expertise. We learn how to listen to each other. And that is the foundation of human understanding.

Terrorism is simply the weapon by which the weak engage the strong.

You can almost measure where you are in life by the degree to which you have begun looking back rather than ahead.

History is a tool used by politicians to justify their intentions.