After explaining the significance of the illustration of a slave in shackles reading "Am I Not a Man and a Brother?" made famous accompanying the abolitionist poem "My Countrymen in Chains" (more about that here) as "the Lance Armstrong bracelets of the day," he took on the history of the man who made the illustration into a mass-produced medallion, Josiah Wedgwood. His story and that story of the image were an anecdote chosen to illustrate the aforementioned four forces elemental in American history. Government and religion work together, government and religion are driven apart, and those dynamics result in things like slavery and the abolition thereof.