My childhood did not prepare me for the fact that the world is full of cruel and bitter things.

My life as a child did not prepare me for the fact that the world is full of cruel and bitter things.

This is a world in which each of us, knowing his limitations, knowing the evils of superficiality and the terrors of fatigue, will have to cling to what is close to him, to what he knows, to what he can do. . .

The peoples of this world must unite or they will perish.

It is a profound and necessary truth that the deep things in science are not found because they are useful: they are found because it was possible to find them.

It is a profound and necessary truth that the deep things in science are not found because they are useful; they were found because it was possible to find them.