Sitting in Selden's easy chair and looking around his flat, Lily realizes that everything looks exactly as it did that day they had tea together so long ago (in the first chapter of the novel). Finally, she speaks; she tells Selden that she's sorry for what she said to him that day he came to see her at Mrs. Hatch's.
Selden responds that he is sorry, too. He notices how tired and run-down Lily looks.
Lily informs him that she left Mrs. Hatch shortly after he gave his advice. He knows this.
As Lily sits there, she realizes that "her presence [is] becoming an embarrassment" to Selden. She feels lonelier than ever as she determines that she has been "shut out from Selden's innermost self." Consciously, she visited because she merely wanted to see him. But it's clear to her now that secretly she was hoping for something else from him (like yet another declaration of love and offer of marriage).
Lily says she has to go, but first she thanks Selden for what he said to her during their walk at Bellomont. She claims that his words have saved her from becoming what so many people thought her to be.
Selden says that he made no difference, that the difference was in Lily herself and always would be. But she doesn't think so.
Lily rises to leave. She tells Selden that he twice offered her the chance to escape from her life, and she refused it because she was a coward. Still, the fact that he believed in her has been a light in the darkness of her life and saved her from the larger temptations, even if she is guilty of submitting to the smaller ones.
"I have tried," Lily says, "but life is difficult, and I am a useless person." She knows that she was merely a cog in the machine of society, and that she has no value as an independent entity now that she has dropped from it.
Selden asks her if she's planning to marry. Lily says that she will have to come to that, but that first she wants to say good-bye to the old Lily Bart, the one that Selden knew and loved. She's leaving her behind, she says, here with Selden.
Selden asks if he can help her, and she remembers him once saying that the only way he could help her was by loving her. He did love her, and it did help her – but that is all in the past.
Yet Lily still feels a "passion" and "flame" between them. She realizes, though she does not say, that she can't go away and leave her old self with Selden. She knows it is still a part of her.
Lily asks Selden to build up the fire for her, as she's cold. As he does so, he notices how much thinner and more angular Lily has grown lately.
When Selden isn't looking, Lily drops the packet of Bertha's letters into the fire.