The Invention of Paper is a Sesame Street storybook based on the "Caveman Days" sketches, featuring Ernie as the Cave King and Sherlock Hemlock as the Royal Smart Person.

In the book, the Cave King is tired of writing on rocks, so he asks the Royal Smart Person to invent something lighter to write on. The Royal Smart Person considers a leaf, a lake and a feather, and finally comes up with paper. The Cave King hails the Royal Smart Person as a genius -- but when the King's paper flies away, the Smart Person gives him a rock to weigh it down, and drops the rock on the King's foot.