That's an Opera?

So here's something that's currently keeping me awake at night (or, at least, ticking over in my mind before I go to sleep):

What makes an opera an opera - and, more importantly, a musical not an opera?

What is the great defining thing that makes one play-with-music-and-songs an opera, while another is 'merely' a musical?

I'm not talking about those jukebox musical thingies which are merely an excuse to string together a number of songs with a flimsy plot. I can understand entirely why Annie Get Your Gun and The Magic Flute should be considered two different things belonging in different categories and genres. But, why is Lamké an opera while Sweeney Todd isn't?

Why is Madame Butterfly an opera, but not Les Miserables? Why The Beggar's Opera, but not The Threepenny Opera? Why is it, that when the national operatic company performs the work of Gilbert and Sullivan, it's considered a bit populist, but okay - but when they try to perform Lerner and Lowe they are met with tut-tutting from various quarters and some people make noises about not buying season tickets?

I mean, really? The national opera company is supposed to have some of the best voices in the country. If they want to take a crack at My Fair Lady I, for one, am interested to see what they can do. Not that I'll get the chance - they'll never tour something like that this far north. But, I digress.

What I'd like to know is where the cut-off is. What's the thing that says "Production A is an opera, while production B is not"? It can't be the plot, the use of music, the way the songs interact with the plot or the structure. Looking at these aspects I can see no plausible reason to separate The Merry Widow from A Little Night Music.

It also can't be the music, because I'll wager that the orchestration of A Little Night Music has more in common with the operas of years past than a lot of the modern operas.

Actually, the concept of "modern opera" is interesting. It sort of makes the whole "what is an opera" question richer, because people are still writing operas. Ninety percent of them aren't any good, and tend to be performed once then justly forgotten - but they are still being written, and they are still being called "operas", not "musicals".

What makes Summer of the Seventeenth Doll, for example, an opera, and therefore more worthy of a performance by the national operatic company than My Fair Lady? Especially since it's nowhere near as good?

I don't think anyone actually likes modern operas. They may appreciate them, but they don't really like them. Modern operas have the same problems as a lot of modern "classical" music, in that the composers have completely missed the point of a tune, and feel they can work perfectly well without one. No one goes home whistling this music. No one feels like going out and buying the sheet music so their kids can perform it at the eisteddfod. No one wants to walk down the aisle to it, or have it played at their funeral. It can be clever, but it's rarely wonderful. The operas of old can be wonderful. Modern "musicals" can be wonderful. I don't know where the composers of modern operas have gone wrong.

I will admit that I didn't actually watch all of the Summer of the Seventeenth Doll. I borrowed a recording of the show and couldn't make it past the opening "number". Perhaps, if I had stuck with it, I would have come to appreciate it by the end, but a) if the overture doesn't have anything enjoyable or interesting in it, the rest of the production probably won't fill you with joy, and b) I can't stand it when people are singing in English and I can't make out a word they're saying. The music obfuscated the words, and I hate that.

Mind you, I find most operas in English have that problem. I think it's the operatic style of singing that makes it so hard to actually understand the words.

Maybe that's what makes an opera an opera? It requires operatic singing? Is that what separates Madame Butterfly from Miss Saigon? The fact that any decent rock singer could perform Chris, but you'd have to be a trained tenor to pull off Pinkerton?

So what happens with musicals like My Fair Lady or A Little Night Music, which don't require operatic singing, but you probably could perform them in that style if you wanted to and you wouldn't do any harm...?