Interpretations aren't black and white
In determining whether an object, action, or character is a symbol, you need to judge the importance that they author gives to it. If the element is prominent and also maintains a consistency of meaning, you can justfy interpreting it as a symbol.
Roberts, pg 151
"Analyzing a literary work as a product of cultural and intellectual history is the task, first, of determining what can be clearly deducible as coming directly out of the major issues existing at the time it was written, and, second, of deciding what is new and permanent--that is, of determining what has been created by the author of the work from ideas prevalent at the time of composition."
Roberts, pg 234
Symbols and allegories aren't new to me. What is new, however is the idea of contextual vs. cultural symbolism. It's not that I don't know what a symbol is, it's just that I'm not used to them being categorized. For me, a symbol is a symbol. I hadn't given it much thought before about whether a symboli in, Shakespeare's Julius Caesar could also occur elsewhere or only in that piece of literature. I'm not sure how I feel about Roberts' claim for how to identify a symbol. If a character is very prominant, why does he have to be a symbol? Does that mean he always has to be a symbol? I'm not sure. If he's the main character, obviously he's going to be prominant, but that doesn't necessarily mean there's a giant symbol lurking in the shadows waiting to pounce on unsuspecting readers at any time. Call me crazy, but I thought literature was supposed to focus on the grey areas, not the black and white. I know there are some stretches that you shouldn't make, but at the same time, literature is great because it's so up to interpretation. I guess I'm just trying to interpret Robert's interpretation of symbols now.
I guess it's really all just up to interpretation. The same goes with analyzing a piece of literature for its historical and cultural values These two chapters (Roberts ch. 10 and 16) should probably be closer together in the book, because they both address similar information.