Though our conduct seems so very different from that of the higher animals, the primary instincts are much alike in them and in us.

Nature shows us only the tail of the lion. But there is no doubt in my mind that the lion belongs with it even if he cannot reveal himself to the eye all at once because of his huge dimension.

In my personal experience I have hardly come to know the wretchedness of mankind better than as a result of the general theory of relativity and everything connected to it. But it doesn't bother me.

There are two ways to live: you can live as if nothing is a miracle; you can live as if everything is a miracle.

Persistence is the most powerful force on earth, it can move mountains.

As our circle of knowledge expands, so does the circumference of darkness surrounding it.

Be a loner. That gives you time to wonder.