"And you remember the story," said the Caterpillar, "of the man who travels millions of years back in time, and accidentally steps on a butterfly; and in so doing, wipes out his own future?"

"Ray Bradbury," I replied. "'A Sound of Thunder'"

He quoted:"... a small thing that could upset balances and knock down a line of small dominoes and then big dominoes and then gigantic dominoes, all down the years across Time."