This statue of Thomas Jefferson, first American Secretary of State and third president, sits in the north entry hall of the Missouri History Museum. I assume it is there because during his administration he arranged the Louisiana Purchase from France, acquiring a huge swath of North America for the young republic.
Jefferson was the principal author of the Declaration of Independence. In one of its famous opening lines, he wrote that "We hold these truths to be self-evident, that all men are created equal." Yet Jefferson was a slave owner. Cognitive dissonance was not an issue at the time.