In our scientific age an understanding of physics is part of a liberal education. Lawyers, bankers, governors, business heads, administrators, all wise educated people need a lasting understanding of physics so that they can enjoy those contacts with science and scientists that are part of our civilization both materially and intellectually. They need knowledge and understanding instead of the feelings, all too common, that physics is dark and mysterious and that physicists are a strange people with incomprehensible interests. Such a sense of understanding science and scientists can be gained neither from sermons on the beauty of science nor from the rigorous courses that colleges have offered for generations; when the headache clears away it leaves little but a confused sense of mystery.