what symbols shows deception in this novel?

The overwhelming theme of deceit in A Doll's House is initially bred in Nora's fear of her secret being discovered. Her fear of being exposed leads her to tell lie after lie. When her lies finally come to light, her marriage proves too weak to bear the strain.

The letters become symbols and proof of deception; the calling card;

"Dr. Rank’s method of communicating his imminent death is to leave his calling card marked with a black cross in Torvald’s letterbox. In an earlier conversation with Nora, Dr. Rank reveals his understanding of Torvald’s unwillingness to accept reality when he proclaims, “Torvald is so fastidious, he cannot face up to -anything ugly.” By leaving his calling card as a death notice, Dr. Rank politely attempts to keep Torvald from the “ugly” truth." (1)