We also see a more fully developed idea of Mary's desire for a home. We learn that she dislikes Tyrone's idea of a home so strongly because she associates it with the death of Eugene, who died when Mary was traveling with Tyrone. Mary associates Tyrone with the traveling home of the theater actor; she thus symbolically spurns the way in which she was forced to live life with Tyrone.
The more Mary uses morphine, the more she tends to delve back into past memories. We thus get a better idea of why Mary uses morphine so much it allows her to leave the present and live in the world of the past, when she was a little girl in a convent. We will see in the last act that Mary idealizes her youth so much that if she takes excessive doses of morphine, she can actually fall into a mental state in which she cannot distinguish between the past and the present. It is important to note, however, that while the men hate Mary's morphine addiction, they themselves are hardly better in their abuse of alcohol. While Mary certainly disappears mentally when she is loaded, the men do the same, even though they think their drug of choice is more acceptable. Of course, we can only assume that Mary will continue to lose more of her dreams as she gets older; O'Neill suggests in this play that people, as they get older, have a tendency to idealize the dreams of the past in such a fashion as to become disenchanted and hopelessly ineffectual in the present.
Of course, this is a very pessimistic outlook, but O'Neill clearly avoids despair by suggesting that there is some redemption through forgiveness. Mary reiterates that she cannot forget the past, but she says that she will try to forgive. While we cannot trust her to make such an effort, it seems that forgiving the past mistakes of Tyrone and her sons is the only way that Mary can stop trying to live in her past dreams and accept the present reality while thinking about a brighter future. Indeed, the title Long Day's Journey into Night has more than one meaning. If the play were simply about Mary, it could be called Long Day's Journey into the Past. There is a dual movement in the play; on one hand, the family is moving forward in time as symbolized by the passing of the day. On the other hand, all the characters, as they get increasingly drunk, travel mentally back in time to happier times when they think they had fewer problems. The title, in its ambiguous use of the word night, seems to suggest the dual nature of the play.
Act III also more clearly shows us the relationship between Edmund and Mary. It is important to recognize that Mary has never stopped seeing Edmund as her little baby son who replaced Eugene, the baby in whom Mary had so much hope. On the one hand, Mary has trouble seeing Edmund as anything other than her invulnerable baby whom she can cure of anything. The prospect of Edmund dying, however, is particularly troubling for Mary because she thinks that Edmund may be God's way of punishing her. So on the other hand, she associated Edmund with her own negligence and potential punishment from God. This double-sided viewpoint leaves complicates their relationship in a fashion that, for a literary standpoint, enriches the characterization of both Mary and Edmund.