That is the most stupid thing yet. I tell you that I could despair of human intelligence when I see what can exist in men’s minds. - Isaac Asimov

In a rather simple way. It merely required the use of that much–neglected commodity – common sense.

People say 'It's as plain as the noise on your face.' But how much of the nose on your face can you see, unless someone hold a mirror up to you?

The image of Hari Seldon reached into open air and the book once more appeared in his hand. He opened it and said: "But whatever devious course your future history may take, impress it always upon your descendants that the path has been marked out, and that at its end is a new and greater Empire!