The Stairway to Heaven thread is interesting, but I think it is somewhat missing the point. Music is a fundamentally different medium for artistic expression than literature. That’s obvious in one way, but I think it bears repeating on the face of so many people trying to find the “meaning” of StH.
Literature is descriptive; music is emotive. The written word is used to convey a specific concept or idea from writer to reader, whereas music is a medium for moods and feelings. Keep in mind that I am not saying that the written word cannot appeal to emotions, or that music cannot communicate a particular idea. I am talking about the primary method by which these various art forms seek to establish the relationship between artist and audience. Literature works on a higher level (i.e. you cannot be moved by a piece of writing if you do not have an intellectual understanding of the concepts within it), but music, as Cecil himself points out, appeals directly to the “reptile brain”. (Note that I am using “higher” here in a non-judgmental context; it does not to equate to “better”.)
StH is not “about” the LotR, not in the sense of trying to be a recap or paraphrase of the story. Instead, it uses the cultural weight of Tolkien’s writing as a buiding block for the response that it is seeking from the listener. This requires some explication on the role that LotR plays in our lives.
LotR is not merely a work of fiction. The imagery of it has become a fundamental part of the Zeitgeist of our times, such that even those who are unfamiliar with the details recognize the core components. (This is not surprising, considering that LotR is itself derivative from an older, more fundamental mythos.) People have a pre-programmed emotional response to its images, because they have already absorbed the intellectual concepts through just living in this culture. In StH, Led Zeppelin is relying upon those emotional responses to enhance the power of their own attempts to reach into the listener’s emotional core. You could think of this as laziness on their part, and if repackaging the emotional wallop of LotR was all that StH had to offer, that would be a fair accusation.
I think it is clear, though, that StH is much more than that. I would place it as a cousin to LotR, not a child; I think that, even without realizing it, Plant was building on the same older mythos that Tolkien was; he was just doing it based on a source that was more familiar to him. (Tolkien, remember, was a professor at Oxford, well versed in the original source materials.) But trying to put a “meaning” on it is an interesting exercise that, in the end, doesn’t mean a hell of a lot.