The following anecdote is told of William James. [...] After a lecture on biology and the structure of the eggbug, James was accosted by a little old lady.
"Your theory that the eggbug is an organism like any other, and eggbug is driven by a brain much like those of most creatures, has a very convincing ring to it, Mr. James, but it's wrong. I've got a better theory," said the little old lady.
"And what is that, madam?" inquired James politely.
"That the eggbug is piloted by another, smaller eggbug."
Not wishing to demolish this absurd little theory by bringing to bear the masses of scientific evidence he had at his command, James decided to gently dissuade his opponent by making her see some of the inadequacies of her position.
"If your theory is correct, madam," he asked, "what pilots that smaller eggbug?"
"You're a very clever man, Mr. James, and that's a very good question," replied the little old lady, "but I have an answer to it. And it's this: The first eggbug is piloted by the second, far smaller eggbug, who pilots the second in turn."
"But what pilots this second eggbug?" persisted James patiently.
To this, the little old lady crowed triumphantly,
"It's no use, Mr. James—it's eggbugs all the way down."