I've had to give this two listens so far. You can hardly expect to write a better melody than that, can you.
I've grown a bit self-conscious about my use of melody recently, not necessarily because there's anything objectively wrong with it because I'm worried I'm a bit too reliant on it and that I use it as a cop-out to avoid trying out any of the many other ways of organising music (melody is a bit of a dirty word in many twentieth-century-onward musical traditions, get with the times). But how can you resist? Aside from stumbling on a melody that excites you being one of the most rewarding musical experiences, it's just too useful an organisational and structural tool to dispense with entirely. I suppose this was more a Wagnerian leitmotif than a 'theme' as such? But I can see how thinking about the ways you can recontextualise, reharmonise, vary, fragment, or translate a melody immediately opens up a vast expanse of formal possibilities. And that's to say nothing of the grandiosity of having it reappear unaltered after one of the symphony's many passages of high drama, which is one of those devices that make music rewarding no matter the context.
It would take many, many listens before I get a feel for the form between movements. It was a very demanding listen, and the impression I got the impression of it being slightly front-heavy on my first try. I have added the first movement to my highlights playlist just for the sake of that theme alone, which I'm inclined to say is my favourite single melody in all of the canon (this has superseded my previous choice of that of the opening of Schubert's ninth, which is similar in some ways). Next time I write for orchestra, I'm going to keep Elgar's orchestration in mind and borrow the texture of the tutti from the introduction. I'll pay a visit to the score, but my guess was strings blended with a bit of mid-range brass.
A bit of bizarre cross-pollination—there was a long sequence in the first movement that made me feel like I was listening to a Rival Consoles piece. I've been listening to his Now Is album and I'm slightly jealous of his imagination, from which he plucks these formal ideas with interplay between parts not unlike the ones you hear large-scale pieces like this. I'll revisit that.