MANDERS. When Oswald appeared there, in the doorway, with the pipe in his mouth, I could have sworn I saw his father, large as life. (1.279)
Oswald's resemblance to his father, noticed by Pastor Manders, is one of the many ghosts in the play. As Mrs. Alving learns more of her son's illness, it's almost though her husband is back in the house.
OSWALD. Yes, I recollect it distinctly. He took me on his knee, and gave me the pipe. "Smoke, boy," he said; "smoke away, boy!" And I smoked as hard as I could, until I felt I was growing quite pale, and the perspiration stood in great drops on my forehead. Then he burst out laughing heartily – (1.290)
Oswald has few memories of his father, but this one is telling. It expresses his father's addictions and slightly cruel sense of humor. It also reveals his mother's sensitivity, and Oswald's own helplessness in understanding what was going on between them.
MANDERS. I will first stir up your memory a little. The moment is well chosen. To-morrow will be the tenth anniversary of your husband's death. To-morrow the memorial in his honour will be unveiled. To-morrow I shall have to speak to the whole assembled multitude. But to-day I will speak to you alone. (1.354)
Setting the play on the anniversary of Captain Alving's death gives the play's action added emotional weight.
MRS. ALVING. Soon after, I heard Alving come in too. I heard him say something softly to her. And then I heard – [With a short laugh] – oh! it still sounds in my ears, so hateful and yet so ludicrous – I heard my own servant-maid whisper, "Let me go, Mr. Alving! Let me be!" (1.405)
These are the same words we hear later from Regina, when Oswald pursues her. Ibsen places a number of echoes in the play – Captain Alving's pipe, the overturned chair in the next room – to make Mrs. Alving feel as though she's in a haunted house.
MRS. ALVING. [Under her breath, but firmly.] No. But then this long, hateful comedy will be ended. From the day after to-morrow, I shall act in every way as though he who is dead had never lived in this house. There shall be no one here but my boy and his mother. (1.439)
Mrs. Alving is determined to bury her husband's memory once and for all. There's an assumption of control there that almost feels like hubris.
MRS. ALVING. [Hoarsely.] Ghosts! The couple from the conservatory – risen again! (1.443)
Hearing Regina say just the same words Johanna said so many years ago, Mrs. Alving is momentarily alarmed. But in her industrious way, she'll come into Act 2 full of ideas, searching for a way to solve the problem.
OSWALD. Everything will burn. All that recalls father's memory is doomed. Here am I, too, burning down. [REGINA starts and looks at him.] (3.84)
Oswald laments the death of his father's memory, even as Mrs. Alving plots for it.
MRS. ALVING. You ought to have known your father when he was a young lieutenant. He was brimming over with the joy of life! (3.110)
Though she spent most of the play attempting to bury her husband's memory for good, the return of her son succeeds her resurrecting and rehabilitating him. Mrs. Alving learns to understand and love the person who had been the object of her hate for so many years.