People are as happy as they choose to be.

The time will come when man will know even what is going on in the other planets and perhaps be able to visit them.

Business men go down with their businesses because they like the old way so well they cannot bring themselves to change. One sees them all about - men who do not know that yesterday is past, and who woke up this morning with their last year's ideas.

I invented nothing new, I simply assembled the discoveries of other men behind whom there was centuries of work.

If I lose a billion dollars, I will have it back in less than five years.

I don’t know much about history, and I wouldn’t give a nickel for all the history in the world. It means nothing to me. History is more or less bunk. It's tradition. We don't want tradition. We want to live in the present and the only history that is worth a tinker's damn is the history we make today.

Whatever you have, you must either use or lose.