Symbol and Metaphor
A symbol represents something other than itself. The meaning can be clear to some, but not others because of culture or experience. A symbol may also have opposite meanings because of culture or experience. The American flag (or any nation's flag for that matter) is an official symbol of that nation, but it may symbolize other things to different groups. To Americans with patriotic feelings, the “stars and stripes” represents freedom, “home”, opportunity, a representative government by the people, etc. Clearly there are also individuals or groups who do not think that the American flag symbolizes those things—in fact, perhaps quite the opposite.
Symbols can change over time, and in different contexts, too, so it's important to understand the use of symbols within the context of their setting.
In A Doll's House, The home and marriage symbolize a very culturally positive thing, but Nora comes to disbelieve in it and feels that their home is a charade of what an actual marriage/ family/home should be. Torvald (and most of the theatre going public at the time) is shocked at this and sees Nora's actions as insane and distructive.
Symbols can be very potent ways to support an idea and they can do so visually as well as textually.
A metaphor makes a comparison between two things or objects. Metaphor comes from the Greek word metapherin, which means to transfer.
A metaphor transfers the meaning or understanding of one thing to a second thing. “She fell through a trap door of depression” does not infer that she fell through an actual trap door, but that her mental state changed to one of depression quickly, perhaps as a surprise, and that she felt “trapped” by her condition.
Metaphors are not only “shortcuts” to expression, they add imagery, and richness of meaning. As with symbols, metaphors are reliant on a shared understanding of the terms, and so can also imply multiple meanings. By engaging the imagination with descriptive imagery, a different part of the reader's (or observer's) brain is engaged and the condition of the description is more empathetic, more visual, and possibly more effective. “The blood-sport of dating” conveys a very different meaning from “the chess game of dating” or “the summer garden of dating”. “Blood sport” implies conquest and damage; “chess game” implies strategy and competition; summer garden can imply fertility, nourishment, and careful tending—but it can also imply overgrowth and weeds. How a metaphor is used, and how it is culturally perceived, is central to its meaning.