How does Northup appeal to abolitionists in the text?

The text makes it seem as though Northup knew it would become a core part of the abolitionist movement in the North. He doesn't hit readers over the head with this, but his descriptions of the terrible things slaves endure, the corrupting influence of the system on white people, the problems for free labor, the hypocrisies of the system in light of the nation's founding principles, and the normalization of family disintegration seem to be calculated to shock and move readers to action. Northup is entirely forthright and thorough; he does not lie or omit or embellish. His work needed to be solid so it could be touted by abolitionists as a visceral example of why slavery must be abolished. Almost every page echoes with Northup's firm belief that slavery was immoral and untenable.