We are Danny's boys - and Danny's girls - and according to the Times yesterday, there are 633 of us. Somewhere back in 2007 we were the lucky ones who got our act together to buy tickets for the whole of Daniel Barenboim's eight-concert cycle of the complete Beethoven piano sonatas at the Festival Hall. Over the past three weeks, tickets to each concert have become some of the hottest must-haves in town. The hall has been turning hopeful buyers away in droves. Already the cycle is being lauded as London's musical event of the year - and even, according to the Evening Standard, of the decade. And now there is just one final concert and four more sonatas before it is all over.

For years, it was at the back of my mind to listen to a complete cycle of the 32 Beethoven sonatas. Somehow it never happened. But when the Barenboim cycle was announced - and all to be played in an unusually concentrated timetable of less than three weeks - I needed no second invitation. These weeks have been ringfenced in my diary for months. Right now, all my waking hours are dominated by Beethoven. Before each concert I have studied the sonatas hard. My iPod is crammed with recorded performances from Artur Schnabel to Mitsuko Uchida (I like Claudio Arrau best). Not everything in life lives up to expectation - but these concerts have exceeded my dreams. When the last recital finishes tomorrow afternoon, I will be bereft. I will find it hard not to cry as Barenboim begins the final movement of opus 111, the one piece I cannot bring myself to study in advance.

Part of the rich emotional reward of these concerts has of course been to do with Barenboim himself. London and Barenboim go back a very long way. There has always been a special affection for him here. Nowadays there is massive respect too, piling up from every direction for all his varied cultural and political achievements. These recitals have therefore been special affirmations. Each time Barenboim has stepped on to the platform he has been greeted with some of the warmest receptions I have heard. If he doesn't get a standing ovation even before he plays a note tomorrow, I will be amazed.

Actually, the real hero of these three weeks is not Barenboim. It is Beethoven himself. I am painfully aware that anything I try to write about the 32 sonatas is bound to be banal, because no one's words can do justice to the imaginative range of the music that Beethoven conjured for the keyboard over his lifetime. So I will take refuge in something that the pianist Louis Kentner once wrote. The Beethoven piano sonatas, said Kentner, should be presented to the first Martian visitor to our planet as proof of what human civilisation is capable of. Here, friend, we should say to the little green men. This is the best of us.

Kentner belonged to a generation of Europeans who had no difficulty thinking about Beethoven in such respectful, even worshipful, terms. Beethoven stood at the summit of musical culture until well into the second half of the 20th century. Everything in music was to some extent conditioned by him. But is that still true? Our age is suspicious of cultural hierarchy. It celebrates cultural relativism. Beethoven is certainly not in eclipse, but his music has become one choice among others. On an iPod his sonatas are just another set of songs.

Listening to Barenboim play Beethoven throws down a challenge to that modern eclecticism. The quality and intensity of these eight recitals insist on the uniqueness of Beethoven's vision. Of course, creative art cannot be entirely reduced to an absolute hierarchy. But is there any greater musical achievement than these sonatas? If so, do tell me. Music of this quality calls on us to be worthy of our inheritance - and pass it on, Alan Bennett-style, to others.

Years ago, when I was a history boy at Bennett's own school, our teacher was challenged by a pupil who assured him that some rock star of the moment was better than his beloved opera, and that it was only the teacher's opinion that opera was better. "I will not allow you to say that all opinions are as good as one another," the teacher reprimanded him. "If someone tells me The Chocolate Soldier is better than Don Giovanni, that's not an opinion. That's wrong."

It is just not possible to disagree with that statement. Some things are just better than others. full stop. In music, few things are better than the Beethoven piano sonatas. Is that an elitist view? Yes it is. But is there anything wrong with it? Not at all. It's not the audience that is an elite for liking the music. It is Beethoven for writing it in the first place.

Barenboim has been performing these sonatas in a week when the culture secretary, Andy Burnham, has ordained that young people at school must get five hours of high-quality artistic and cultural activity a week. This is an admirable decision in principle, as long as it can be sustained in practice for all. But it will be sustainable only if we believe in it, and if it is not subverted by the insidious and widespread belief that Shakespeare or Beethoven or Cezanne are somehow too difficult or, even worse, not "relevant" enough for today.

The best art is not the only art, but it can be uniquely ennobling and it ought to be available to everyone. If that smacks of a belief in educational "improvement", I plead guilty as charged. I think musical taste and public values need improving. This would be a lot easier if the BBC was willing to put classical music or theatre on its main channels, as it once did. But those days are gone, sadly.

Better reverence than irreverence. Lenin once explained that he could not listen to the Appassionata sonata too often because, wonderful and immortal though it was, the sonata might make him falter in his task of smashing his enemies' heads without mercy. Doesn't that sum up why the world is so much better off with Beethoven than with bolshevism?

There are few things I know with any confidence. One is that, in these piano sonatas, Beethoven went further towards expressing the vast scope of the human spirit in sound than anyone before or since. The last movement of the final sonata takes that process as far as even he was able. Both it and the edifice of 32 sonatas on which it rests are Beethoven's imperishable achievement. And yet, in an immensely significant way, the achievement belongs to us all.

martin.kettle@theguardian.com