In what way does Douglass use his autobiography to make his case against slavery?

In the first book, Douglass offers examples of how the slaveholders become corrupted by their own institution, and leaves the reader to devise his own conclusion. "I have an abundance of such illustrations of the same principle, drawn from my own observation, but think the cases I have cited sufficient". He leaves the reader, in this instance, to imagine more ways in which the master unintentionally.