Benjamin Franklin with a great mind... some joke. He outrightly justified slavery and condemned Africans as lower speicies whose fate was to be enslaved.
Thomas Payne was the brain behind the idea of American Independence: 1/5 of the Americans read his Common Sense; otherwise the war might have failed miserably.
By the way, he was not just a "man of his times". Note that there were people like John Adams who wanted to free slaves and yet was a president. Even Washington freed all his slaves after his death. France freed all of her slaves of West Indies in 1793 and gave all races rights to vote - later suppressed by Napoleon.
Edited by Evildoer