Do you know how zen koans work? They help you understand yourself. They don't do it by telling you about yourself, but rather by tricking your mind into paying attention to nothing other than yourself, even though you might not consciously want to.

In the same way, symbolism is intended to trick the mind into grasping a concept it consciously has problems with understanding, or perhaps outright disagrees with. It's like grinding a vitamin into dogfood--the dog won't notice, but it's getting healthier. You might be an ardant anti-___ist and never want to hear a single word on ____ism, but a carefully crafted allegory about ____ism might have you more of a believer than you knew.