What symbolism is represented in A Doll's House?

An interesting symbol that is usually not mentioned is the dance, the Tarantella, that Nora practices for Torvald. 

During this dance, Nora is full of excitement, nervous energy and agitation, so she dances wildly and Torvald is displeased with her. Symbolically, the dance, can be seen as Nora's attempt at a full and satisfying life, and Torvald, obviously, does not approve. Nora could never have a more satisfying life with her husband, he does not approve.

He refers to Nora with cute little animal names, like a pet.

"Come, come, my little skylark must not droop her wings. What is this! Is my little squirrel out of temper? (Taking out his purse.) Nora, what do you think I have got here"? Act I

"It's a sweet little bird, but it gets through a terrible amount of money. You wouldn't believe how much it costs a man when he's got a little song-bird like you!" Act I

She is treated like a doll, who must look pretty, and be put on a shelf to be controlled. Nora is not a real person to her husband, in his mind, she can never handle responsibility outside the house. Therefore, when Torvald finds out about Nora's deception it is such a betrayal, a scandal for him.