God gave me the stubbornness of a mule and a fairly keen scent.

He who finds a thought that lets us a little deeper into the eternal mystery of nature has been granted great peace.

One must console oneself with the thought that time has a sieve through which most of these important things run into the ocean of oblivion and what remains after this selection is often still trite and bad.

Where you see difficulty, I see opportunity.

I shall never believe that God plays dice with the world.

Mere thinking cannot reveal to us the highest purpose.

It is the theory which decides what we can observe