I finished reading Norman Lebrecht's 2010 book, Why Mahler: how one man and ten symphonies changed the world yesterday, and have done a rather hastily-written review here, so I'm not going to repeat what I said.
I just wanted to make a few notes about my experience of Mahler over a long period of time, which admittedly has been entirely through recordings. I've never actually had the opportunity, as far as I recall, of seeing his work performed live.
The first time I heard anything by Mahler was when I bought a record of his Fourth Symphony through a record club I belonged to, back in the late fifties/early sixties. They'd post out their record of the month, and you could either keep it (and pay for it) or send it back and get something else, or just get nothing. Anyway, the symphony started with sleighbells. Odd. And then in the fourth movement a woman began singing, sweeping along with the orchestra at a great pace - Leonard Bernstein was the conductor.
Singing in a symphony? Well of course I was young and naive, and didn't know that having singers in a symphony was hardly new - Beethoven had done it way back in the Ninth, though I probably wasn't aware of that then, being only a callow teenager. (I was ignorant enough to have been astounded to hear from another piano player that Shostakovich was not only still alive but still writing symphonies.)
But Beethoven's Ode to Joy in the Ninth (a jolly little folk song he commandeered which drives me mad wherever I hear it) was nothing compared to the joyous and delightful singing in the Mahler. Mahler's own songs often made their way into his symphonies in some form or other, and if you know the songs you'll recognise them in the symphonies; or vice versa. He's a very self-referential composer, which makes you think, when you hear one of his symphonies for the first time, that you've heard bits of it before. You probably have. He seems to use ideas from one symphony to the next, and certainly his style is so peculiar to him that on hearing a piece of music you can often identify it as being his: there are phrases, mannerisms, ways of orchestrating things that appear again and again.
This is hardly unusual: many composers' "voices" are surprisingly unique, in spite of the fact that they're working with the same bunch of notes. Mozart is recognisable almost invariably, so too Beethoven, Tchaikovsky, Shostakovich and dozens of others.
But Mahler is a little different. I remember Chesterton (I think it was) saying that the books of Charles Dickens were like chunks cut from one long cloth. They were full of Dickensian stuff; and even where he plans out his books more carefully, it's unfailingly Dickens. Mahler, to me, seems the same. It's as if he had one enormous symphony inside him and just chopped off an hour or so at a time for the next one.
That's a simplification, of course. As is the comment about Dickens. And yet both have an element of truth in them.
I was a bit surprised the other day to find that I had five of Mahler's symphonies on CD. Which means that I've listened to a lot more of his music than I'd thought (apart from what I've heard on the radio over many years). I don't have the Symphony of a Thousand (it's number 8), so watched this on You Tube yesterday. The wonderfully enthusiastic Gustavo Dudamel conducts a combined - and enormous - orchestra made up of the Los Angeles Philharmonic and the Simon Bolivar Youth Orchestra. Four different choirs are involved, massed up and up beyond the orchestra on stands. (The youngest choir sings without music, and occasionally you see one of them turn to another and maybe tell them they've sung something wrong, or else one spies the camera and gives a grin.) Apparently there are 1400 people involved. Crikey. There are seven soloists as well.
Mahler seems to have delighted in going for the extreme. In at least one other of his symphonies (no 2, the Resurrection) he lists out the instrumentation required, then adds, as the score progresses, twice as many of this and six more of those, as though musicians would suddenly appear out of the woodwork during the course of the performance. I'd love to see it happen, but it's probably not going to.
I don't know whether Mahler's Symphonies changed the world. Certainly hearing the 4th for the first time was a delightful surprise, but did it change my world? Possibly, but not in a way that made me turn direction. I still get a lump in my throat at hearing the singing beginning her song in it, but then music of all sorts does that. Listening to Mahler's 2nd Symphony the other day, which also has a large choir and soloists, I got all emotional when the choir came in, super-super softly, and just sang about the life after death, about being raised from the dead. Does it change my world? Well, I don't know, but it certainly adds to it.