How does Taper's letter reverse the rhetoric, common among white Americans, which saw the United States as a land of freedom and the British empire as lacking in liberty?

In his letter, John Taper reflects on the life that he enjoys in Canada. Back in the United States, Taper was a slave in Virginia. He lacked rights and liberty, and could not make decisions about his own life. Because of this, Taper decided to run away. He settled in Canada, which at that time was part of the British empire, and where slavery was illegal. Taper reveals that he has a good life in Canada and that he enjoys comforts that he could never have enjoyed in the United States. This presents the United States as a land of bondage and Canada as a land of liberty, which is significantly different from the dominant view of the United States as a land of freedom.