The two letters Robbie produces represent the two aspects of his desire. One is graphic and sexual while the other is heartfelt and sincere. Both aspects are part of healthy love; however, because Robbie’s emotions are repressed, his sexual desire expresses itself in vulgar obscenities. Writing the vulgar letter provides Robbie sexual release. Afterward, he feels relieved enough to write the intended letter by hand.

The vulgar letter symbolizes both intrapersonal and interpersonal communication problems. His more refined romantic feelings are more difficult to access than his sexual fantasies, suggesting that in the emotionally repressed world of the Tallises, expressing sincere emotion is more shameful than violent sexuality. While Cecilia is able to interpret Robbie’s true feelings from the vulgar letter, Briony is not. Briony is not old or mature enough to understand the complexity of adult emotions, nor does she know the nuances of Robbie and Cecilia’s relationship. She mischaracterizes the intent of the letter, and this failure has terrible consequences.

The others’ reaction to the letter symbolizes the way in which unspoken agendas operate. Emily disapproves of Jack’s sponsorship of Robbie’s education, and he has ignored her suggestions that they stop paying for Robbie’s tuition. When Emily reads the letter, she folds her resentment of her husband and her class prejudice into her estimation of Robbie’s guilt.