How does Frederick Douglass make his case against slavery in his autobiography, "My Bondage and My Freedom" ?

The main theme of the novel is surely slavery and all the bondage which this “institution” implies. The main character tells a story of his life, and presents detailed descriptions of his life as a slave. But he delves deeper in his contemplations of slavery and the slave system than only retelling what he has come through when being a slave. The essence of the very slave system is rooted in absence of humanity and goes years back when his ancestors were stolen from Africa and brought to America with a purpose to be sold as property. But with years passed the essence of slavery became wider in its interpretation and slavery itself becomes an institution and is often personified by the narrator: “Slavery can change a saint into a sinner, and an angel into a demon”. With consideration upon slavery system the narrator does not blame the slaveholders as, ti his opinion, they are the victims of the slavery the same way as the slaves. It is absence of humanity which is to be blamed.