Robert Peate said this quote

What could be better for slave owners than slaves who think they’re free? This is the greatest trick ever pulled: a nation of slaves who think they’re free. Slaves must be fed, housed, even clothed. But if they must feed, house, and clothe themselves as ‘payment’ for their work, this removes burden from the slave owner—while the same work is performed and accomplished, to the benefit of the slave owner. The best part is that slaves who think they’re free will never work to end their slavery. They will look down on those who do not work. To work to end their slavery, they must first learn they are slaves. This is the hardest task of all: to free their minds.