A solo performance by Philip Glass asks many questions of the listener. His is a strangely simple and seemingly perpetual sound - one where a theme is repeated so often that one's instinct immediately warns of oncoming boredom. And, although this fatal state never actually arrives, Glass takes every chance that it might.
Certainly he's a very amiable presence between pieces, but the performance itself is intense and relentless - one which tends to leave an audience more hypnotised than elated. Relying entirely on the music itself, there's little by way of pyrotechnics and even less by way of "entertainment." Rather than being simply invited to gasp at musical fireworks from a distance, the music of Philip Glass makes the audience uniquely part of what is happening on stage - steadily and quite mysteriously.
To ears more used to more "conventional" music, it perhaps shouldn't work at all. And one wonders how Philip Glass actually got to this point. What sort of rigour was involved in dispensing with so much of the music which went before? And what influences produced a composer/performer with such a definite and potentially unsuccessful approach? To have made his "vocational choice" by the age of 10 suggests a freakish childhood - but that was never the case. The Baltimore days of Philip Glass were never rarified or musically isolated. Back in 1940s Maryland there was plenty of "ordinary" music too.
"Oh, yes, I did all that. I sang a lot of the popular music of the time. But I was very lucky because my father ran a small record store - what we call in America a mom and pop store - and all that music was available to me. In fact, I had a little singing routine I did with some other kids. I had a little ensemble and we would sing popular songs at get-togethers. This was right after the war and we did show-tunes, Broadway things and music that was associated with movies like Oklahoma, South Pacific and so on - popular commercial theatre music that was part of American life at the time - even Gilbert and Sullivan. You really had to be there!"
But Glass was to compose music which was a million miles from Broadway. By 1974 he had a large collection of new music in his repertoire. In 1976 he wrote the hugely influential Einstein on the Beach with Robert Wilson, and since then has pursued everything from opera to film score to dance - all of it with its origins in his early attraction to modern and very difficult music. It was a music which, back then, was very cutting edge and not an obvious choice for anyone.
"Well, my father guided me in a certain way because he brought music back from the store. And this was music that he didn't sell. He wasn't an educated musician and so he would bring this music home and try to figure out what was selling and what wasn't selling. So, he would listen to this music which wasn't selling over and over again and he ended up liking it. It would have been in those days, very contemporary music - Prokofiev, Shostakovitch, Stravinsky and Debussy. So, he got very interested in that music because he was trying to figure out why he couldn't sell it. But it's that thing that we all know - as things become more familiar, the strangeness begins to vanish and the inner beauty of the work begins to emerge."
And so Philip Glass grew up in a house where, as he puts it, they were constantly making these "experiments with music". He was also, at this time, undertaking his conservatory training, playing in churches and also performing popular tunes in little school orchestras. And from this musical mix of Baroque, tin pan alley and abstract music, Glass found himself becoming increasingly drawn to the latter. By the time he was 15-years-old, he was studying the scores of Webern and Charles Ives - and enjoying both the thrill of the new and the lure of the strange.
"I think it was partly that - because it was new and different. It was also because it seemed to speak in a modern vernacular. But then, as I became more familiar with modern music, I left that very abstract music behind in a way. I lost interest in it at a certain point, but my first encounter with experimental music had been with the more abstract music.
"There was an intellectual interest in it and I was intrigued by it and I was looking for a language in modern music that would correspond to the language in the modern world that I lived in. The thing about playing the St Matthew Passion - that's all very well and good for the church - but what do you play when you're not in the church ? What is the music of our time?"
Others were thinking similarly. And, while they were never a "school" as such, Glass was part of that scene which included La Monte Young and Steve Reich. But, as he talks of their desire to write concert music which was "of the time", he pre-empts the obvious question about popular and rock music - which undoubtedly was already in place as the actual music of the time.
"Popular music always had a certain appeal to me but I really felt the challenge of concert music. I had more of an aptitude for it. In a funny way, in my mature years I was able to meet up with people in the world of popular music and find that it has not been a very hard bridge to cross.
`Over the past 10 years I have written with people like Suzanne Vega, Natalie Merchant, Michael Stipe and Paul Simon and I wouldn't be doing it if I wasn't interested in it. I'm especially interested in certain composers like Brian Eno, David Bowie and Zappa. And this is something I'm fond of saying about talent - it's the most democratic aspect of humanity. It turns up anywhere - without benefit of university degrees, regardless of skin colour, gender or age. Talent is just talent - whether it's John Lennon or Paul Simon you can put them up against someone of any genre, whether it's Strauss or Mahler, and you can't say who is the better songwriter. I would be very reluctant to say that the guy with the conservatory degree is the better songwriter. It might not be true."
Hugely influenced by the likes of John Cage and Ravi Shankar, Philip Glass approaches his work as a composer who is also a performer. He talks eagerly of the cycle of activity involved - from conception to performance - and takes huge pleasure in the act of playing his music for an audience.
His next major project will be performances of his newly composed soundtrack to the 1931 Dracula. Joined by the Kronos Quartet, he will perform the score live to the movie itself. It's yet another exciting prospect for this most prolific of musicians, and yet one suspects that he gets most pleasure from what he did in Dublin - just himself, his music and his piano.
"I call it the essential experience for the composer. You have conceived the work, you have written the work, you've rehearsed the work and then you're performing it in front of the public. The entire creative cycle is contained in that evening. I'm there without dancers and lights and so on.
"I do about 20 concerts a year which are just me and solo piano and there's a tremendous reality check involved. It's the most intimate and direct communication that we have with an audience. Of course, you have the greater responsibility because, if someone makes a mistake when you're playing, it's you for God's sake - you can't look over your shoulder at anybody else!"