Please explain how is irony used to show slavery's dehumanizing effect in the quote: "An unpardonable offense to teach slaves to read in this...

Douglass speaks about
the ways in which slavery twists the ideas of what is decent and good. After his slave mistress,
Mrs. Auld, teaches him the rudiments of reading, her husband, who has far more experience as a
slave master than she does, roundly criticizes her. He says that reading will forever make a
slave unfit for slavery.

involves the use of something that is contrary to
what one expects. Reading is a positive good, as is education, but in the slave-holding
South,...