As far as I remember from literary classes, some schools (or at least a very influential one) see the author's intention as irrelevant to the text's meaning.
This made me remember reading Lord of the Flies in high school, and the teacher kept coming up with all these metaphors and symbolism. I kept wondering if the author really had intended that.
Another example is Lord of the Rings. At least the author later wrote a forward explaining there was no allegory attached to the story. It was just a fantasy story.