Civilizations, I believe, come to birth and proceed to grow by successfully responding to successive challenges. They break down and go to pieces if and when a challenge confronts them that they fail to meet.

It is a paradoxical but profoundly true and important principle of life that the most likely way to reach a goal is to be aiming not at that goal itself but at some more ambitious goal beyond it.

The course of human history consists of a series of encounters between individual human beings and God in which each man and woman or child, in turn, is challenged by God to make his free choice between doing God's will and refusing to do it.

We human beings do have some genuine freedom of choice and therefore some effective control over our own destinies. I am not a determinist. But I also believe that the decisive choice is seldom the latest choice in the series. More often than not, it will turn out to be some choice made relatively far back in the past.

The equation of religion with belief is rather recent.

My advice to any traveler who is traveling in order to learn would be: 'Fight tooth and nail to be permitted to travel in what is technically the least efficient way.'

The supreme accomplishment is to blur the line between work and play.