how does mr. auld try to inhibit douglass from to read and write? how does he succeed in attaining his aim?

Mr. Auld forbade his wife to continue with Frederick's instruction. He explained that if a slave was taught to read, it would spoil him and make him unfit to be a slave. He would become unmanageable and freethinking as well as discontented and morose.

When Douglass heard this he was astounded; "it was a new and special revelation, explaining dark and mysterious things, with which my youthful understanding had struggled, but struggled in vain." The pathway from slavery to freedom was now illuminated. Even though Douglass was sad to lose his instruction from his mistress, he was grateful to have the reality of the power of learning made clear to him.

Mrs. Auld's cessation of instructing Douglass was her first step on the road to ruination. She went above and beyond her husband's request to leave off teaching her slave letters, and soon was most vigilant in making sure Douglass was nowhere near a newspaper. He was watched quite closely, but his own desire to read and write triumphed.