A well-known scientist (some say it was Bertrand Russell) once gave a public lecture on astronomy. He described how the earth orbits around the sun and how the sun, in turn, orbits around the center of a vast collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said: “What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise.” The scientist gave a superior smile before replying, “What is the tortoise standing on?” “You’re very clever, young man, very clever,” said the old lady. “But it’s turtles all the way down!”

—Stephen Hawking

Professor Hawking’s “Turtles All the Way Down” anecdote, like any good anecdote, has had a long and exotic career. In the oldest telling of the story, it relates a Hindu myth claiming that the world rests on the back of an elephant, which stands upon a tortoise. (There is no such Hindu myth, but never mind. Fabricated Hindu myths, like imaginary African proverbs and Native American sayings no Native American ever said, are a cinema screen upon which a certain kind of mind projects itself.) The story crops up in the work of David Hume, Henry David Thoreau, and Lewis Carroll. Bertrand Russell himself related the story this way:

If everything must have a cause, then God must have a cause. If there can be anything