One of the tragedies of what is loosely referred to as classical music is the way in which it has become an ossified museum piece.
Once upon a time composers such as Haydn, Mozart, and Mahler used contemporary popular song and dance melodies as a reference point for their own compositions. They also frequently made allusions to contemporary social concerns.
But the 20th century has seen the works of these composers turned into sacred pieces to be revered in the setting of the sombre concert hall venue. And modern classical composers have, by and large, found themselves unable to engage with popular music.
All this has further alienated classical music from a popular audience. But there are exceptions to this rule – such as the US composer John Adams, whose works are being celebrated this month with a retrospective at the Barbican in London.
Adams originally emerged from the Minimalist movement that took root in New York in the 1960s. The Minimalists – whose pioneers included Steve Reich, Philip Glass and Terry Riley – were reacting against what they saw as the dry academicism that dominated composition at the time.
The prevailing fashion was centred on developing the 12-tone system of Arnold Schoenberg. This was based on rejecting harmony and repetition in favour of harsh dissonance and constant unexpected turns in the melody.
The Minimalists argued that 12-tone was making classical music even more inaccessible to a wider audience. Instead they took their inspiration from rock music and electronica to create what they called 'phase patterns'.
Simply put, this was a method of using continuous repetition of basic melodies with subtle changes in harmony and pitch to create a sense of something moving very fast and very slowly at the same time.
One of the problems with the Minimalist composers has been their inability to develop their style much over the last 30 years. John Adams, again, is an exception. He has tried to break out of the restrictive precepts of the Minimalist system to create more varied and expressive music.
As such he has composed energetic fast-paced pieces such as Short Ride In A Fast Machine and Fearful Symmetries, while on the other hand producing more lyrical pieces such as Berceuse Elegiaque and Harmonielehre.
Adams has also used his music to tackle contemporary political questions, particularly issues of war and global politics. His first opera, Nixon In China, was composed in 1987. Its subject, as the title suggests, is the historic 1972 visit of US president Richard Nixon to Mao Zedong's China.
To use such a piece of contemporary history as the subject for opera was itself an innovation in modern classical music.
Adams and his collaborator Alice Goodman, who wrote the words on which the opera is based, are careful not to create caricatures out of their main protagonists.
Instead the opera is a meditation on the cynism of power. Nixon is obsessed with his place in history, his sidekick Henry Kissinger is a brooding presence in the background, while Mao constantly needles Nixon over the Vietnam War.
Adams's second opera, completed in 1990, took on an even more difficult subject. The Death Of Klinghoffer deals with the 1985 hijacking of the cruise ship Achille Lauro, during which Palestinian hostage takers killed Leon Klinghoffer, a disabled Jewish passenger.
Again, Adams and Goodman avoid stereotypes and crude political points. The whole opera is essentially a debate between two groups who have suffered appalling persecution in the 20th century.
Although any clear identification with either side is avoided, the point made again and again by the Palestinians is the hypocrisy of the Zionists using the Holocaust to justify their persecution of Palestinians.
This made the opera controversial enough to be banned from performance in the US, both at its premier in 1991 and again in New York just after 9/11.
Unfortunately, Adams's response to 9/11 was musically unoriginal and politically crude. His piece commemorating the tragedy, On The Transmigration Of Souls, is little more than a musical drone with the names of those who died intoned over it.
Overall, however, Adams manages the difficult feat of composing music that is innovative, modern and yet highly accessible. And even when he is not being explicitly political, his nervous, driven and expressive style accurately reflects life in today's urban, industrialised world.
For more details of the John Adams events at the Barbican go to www.barbican.org.uk.