Go search where you will, roam through all the monarchies and despotisms of the Old World, travel through South America, search out every abuse and when you have found the last, lay your facts by the side of the everyday practices of this nation, and you will say with me that, for revolting barbarity and shameless hypocrisy, America reigns without a rival. (84)

In the last sentence of the speech (which is also the final paragraph), Douglass strikes a knockout punch at Fourth of July celebrations. The Fourth of July is a celebration of American independence from Great Britain, sure, but it has also traditionally been a day to celebrate how much greater, how much more moral, and, ahem, how much better America is than other countries.

Douglass says nope, sorry. Check out the rest of the world. They're getting their act together re: slavery. But not America.

Also, he can't believe how they're cluelessly celebrating their freedom while America holds slaves. Hypocrites much?

We're willing to bet the listeners felt thoroughly chastised, shamed, and awkward at the end.