Analyze the purpose to why Thoreau includes the allusion of the "peculiar institution" in his argument of Civil Diosbedience

Thoreau is referring to slavery. He points out that slavery was not unique to the American South, it existed all around the world. 

"Talk about slavery! It is not the peculiar institution of the South. It exists wherever men are bought and sold, wherever a man allows himself to be made a mere thing or a tool, and surrenders his inalienable rights of reason and conscience. Indeed, this slavery is more complete than that which enslaves the body alone.”