Truth.

Linda takes a passage in the book to explain exactly what was about to happen to the audience. However she does it for a very good reason. When Linda has an affair with Mr.Sands she tells the reader before hand that she did something wrong, something she wasn't proud of, but she did it with a cause in mind. This makes it so much easier to establish a relationship with the character, because the reader feels like they're being confided in, which helps strengthen the relationship. Linda coming forward and explaining first hand that what she did was wrong and she knows it, is a huge step to the readers trusting her.