Darwin's Concession and the Bacterial Flagellum Notebook

This notebook features Darwin's concession regarding what sort of discovery would undermine his evolutionary theory: “If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case.” What follows is an artist's rendering of the bacterial flagellum, the remarkable and irreducibly complex cellular propeller made famous by Michael Behe in his book Darwin's Black Box, and the words "Dear Darwin: Meet the bacterial flagellum."