To be able to concentrate for a considerable time is essential to difficult achievement.

But as the work proceeded I was continually reminded of the fable about the elephant and the tortoise. Having constructed an elephant upon which the mathematical world could rest, I found the elephant tottering, and proceeded to construct a tortoise to keep the elephant from falling. But the tortoise was not more secure than the elephant, and after some twenty years of very arduous toil, I came to the conclusion that there was nothing more that I could do in the way of making mathematical knowledge indubitable.

Religion is something left over from the infancy of our intelligence, it will fade away as we adopt reason and science as our guidelines.

Of these austerer virtues the love of truth is the chief, and in mathematics, more than elsewhere, the love of truth may find encouragement for waning faith. Every great study is not only an end in itself, but also a means of creating and sustaining a lofty habit of mind; and this purpose should be kept always in view throughout the teaching and learning of mathematics.

Neither the Church nor modern public opinion condemns petting, provided it stops short at a certain point.

In mass cruelty, the expulsions of Germans ordered by the Russians fall not very far short of the atrocities perpetrated by the Nazis.

There is an artist imprisoned in each one of us. Let him loose to spread joy everywhere.