Appearance and reality
Krogstad appears to be a bitter, vengeful extortionist until he is reunited with his true love, Mrs Linde, when he becomes more merciful and generous. Mrs Linde first strikes us as self-sufficient, but we learn that she feels "empty" now that she has no one to look after. Dr Rank acts the role of friend to Torvald and Nora, but we later discover the true motive for his daily visits: he is in love with Nora.
The role of women
Women could not conduct business or control their own money, for which they needed the authorization of the man who 'owned' them - husband, brother or father. Moreover, they were not educated for responsibility. Nora falls foul of both injustices, by taking out a loan without the authority of her husband or father, and by believing, out of ignorance of the world, that she could get away with forging a signature.
In a sense, single women like Mrs Linde were freer than married ones, in that they had a right to the money they earned and did not have to hand it over to the man of the family. But the employment open to women was restricted and poorly paid, as we see in Mrs Linde's case: there was clerical work, teaching or domestic service. Also, women's work was grindingly dull, and likely to leave an intelligent woman like Mrs Linde "empty" inside.
Marriage was a trap in another sense, too. Though divorce was available, it carried such a social stigma (not just for the woman, but also for her husband and family) that few women saw it as an option. This is why Torvald would rather have a pretend marriage, for the sake of appearances, than a divorce or an amicable parting.
The female characters of Nora, Mrs Linde and the Nurse all have to sacrifice themselves to be accepted, or even to survive. Nora not only sacrifices herself in borrowing money to save Torvald, but she loses the children she undoubtedly loves when she decides to pursue her own identity. Mrs Linde sacrifices the true love of her life, Krogstad, and marries a man she does not love in order to support her dependent relatives. The Nurse has to give up her own child to look after other people's in order to survive financially. What is more, she sees herself as lucky to get her lowly job, since she has committed the sin of having a child out of wedlock. In Ibsen's time, women who had illegitimate babies were stigmatized, while the men responsible often escaped censure.
Ibsen does not suggest solutions to what was called "the women question," his aim being rather to shine a spotlight on problems that few were willing to talk about. He left the task of finding answers to others.
The individual and society
Torvald defines his life by what society finds acceptable and respectable. He is more concerned about the attractive appearance of his wife and home than he is about his wife's happiness. When she tries to convince him to keep Krogstad in his job, his main concern is what the bank employees will think of him if they believe he has been influenced by his wife. And even after he has rejected Nora, he wants her to remain under his roof to preserve the image of a respectable marriage.
Much of Krogstad's life has been affected by society's moral standards. He spent some time in disgrace after committing an "indiscretion," and resorts to blackmail in an attempt to keep his job as a mark of respectability. His threat of blackmail gains its power from the immense authority that individuals vested in society's moral standards: if nobody cared much what society thought, then Krogstad could tell all and no one would be harmed.
Nora begins the play fulfilling a role that society prescribed for women - that of dutiful wife and mother. Her role is restricted to such activities as creating a beautiful home, meeting the needs of her husband and children, and singing and dancing prettily and seductively for her husband. Ibsen does not suggest that there is anything inherently wrong with such duties, but he does point out the dangers of having an individual's life defined by society in a way that ignores their personal identity and journey. In leaving Torvald and her children, she will outrage society and stigmatize herself. This is a terrible price to have to pay for self-fulfillment, but inevitable, given that society and the individual are so much at cross-purposes. Society wishes to preserve the status quo, whereas self-fulfillment often means pushing and breaking boundaries.
The first interactions we see between Nora and Torvald are about money; she knows that if she behaves in a certain subservient way, Torvald will give her more money. She later uses similar manipulations on Dr Rank, drawing attention to the way in which women in an unequal society tend to barter sexual favors in return for money.
Torvald teases Nora about being a spendthrift: this is his way of displaying his dominance over her, since he who controls the money controls the relationship. Nora's attempt to take partial control of the money in their marriage by taking out the loan ends in disaster, as Torvald feels morally shamed by her action. It has put him at the mercy of Krogstad and, it is implied, compromised his standing as a man and a moral member of society.
Before Ibsen revolutionized drama through his embrace of realism, many plays contained a character with the role of 'moral foil', a commentator on the actions of others. Ibsen partially subverts the notion of the 'moral foil' in the characters of Dr Rank and Mrs Linde. They arrive in the play at the same time, which alerts us to the fact that they share a dramatic purpose. To some extent, they are truth-bringers in the false setup of the Helmer marriage. Mrs Linde decides not to persuade Krogstad to recall his letter, as she believes it is time the Helmers faced the truth about their marriage. And Dr Rank talks to Nora as the intelligent person she is, not as the silly doll-child that Torvald prefers. But these characters turn out to be as fallible and morally compromised as most people are in real life. Mrs Linde has betrayed her true love, Krogstad, by marrying another man for money and security, an act which has left her "empty." And Dr Rank is not entirely the selfless friend to Torvald that he first appears to be: he visits because he is in love with Nora.
A Doll's House: Theme Analysis