When he's a young boy about the age of seven or eight, Frederick is sent to Baltimore to live with Mr. Hugh Auld, the brother of Captain Anthony's son-in-law. Initially, all seems well at the Auld residence; Mrs. Auld treats Frederick with great kindness and consideration. For one thing, she doesn't demand the kind of subservience that he's always been expected to show in the past. Moreover, she teaches Frederick his ABC. Again, this is a whole new experience for Frederick, and a welcome one at that.
But when Mr. Auld finds out about this, he's absolutely furious and orders his wife to desist at once. Auld thinks that education of any kind is dangerous for slaves as it puts ideas into their heads. If slaves can get an education, then they'll come to realize that there's a better world out there away from the plantation, where they can be free and where they can make something of themselves. Ironically, Mr. Auld's contemptuous dismissal of educating slaves is itself very educational for Frederick. For he's now witnessed at first hand one of the most effective strategies that white men use to keep black people down. This is a lesson that will stand him in good stead for the rest of his life.