About Newton: Nature to him was an open book, whose letters he could read without effort.

For science can only ascertain what is, but not what should be, and outside of its domain value judgments of all kinds remain necessary. Religion, on the other hand, deals only with evaluations of human thought and action: it cannot justifiably speak of facts and relationships between facts.

When you are courting a nice girl an hour seems like a second.

Stupidity is a personal achievement which transcends national boundaries.

The truth of a theory can never be proven, for one never knows if future experience will contradict its conclusions.

Arrows of hate have been aimed at me too, but they have never hit me, because somehow they belonged to another world with which I have no connection whatsoever.

The next world war will be fought with stones.