Conflating Symbolism and Allegory

Ursula K. Le Guin's famous "gerbil" rant was about this: "In many college English courses the words myth and symbol are given a tremendous charge of significance. You just ain't no good unless you can see a symbol hiding, like a scared gerbil, under every page. And in many creative writing courses the little beasts multiply, the place swarms with them. What does this Mean? What does that Symbolize? What is the Underlying Mythos? Kids come lurching out of such courses with a brain full of gerbils. And they sit down and write a lot of empty pomposity, under the impression that that's how Melville did it."

This often arises from the improper conflation of symbolism (which doesn't imply a one-to-one correspondence and doesn't need to have one and only one meaning that can be stated in a simple declarative sentence) and allegory (which implies a one-to-one correspondence and a stated specific meaning).