America's historic sense of mission has been redefined to mean the creation of a single global free market. - Eric Foner

Essentially what Lincoln said is slavery is a form of theft, the theft of labor, one person stealing another person's labor without that person’s permission.

Even as the United States has risen to become the predominant international power, however, conflict has persisted over the nature of American society itself and what its role in the world should be.

Slavery was a byproduct of the quest for profit—economic actors were the architects of the slave plantation systems that came to dominate American society from the Southern United States to the Caribbean and Brazil. It was merchants and planters, not statesmen and jurists, who determined that slave labor was more profitable than free. ... This history constitutes a welcome corrective to the fashionable view that free markets automatically promote social justice.