SEVERAL weeks ago, I earmarked this slot for some consideration of a single piece of music, and not an epic.

The piece in mind is a short Beethoven Piano Sonata: not one of the giants or big name sonatas, but actually a sonata quite modest in scale. Its number is opus 90, and its key is E minor. Before going any further, the initial reasons for electing to take such a close focus on a single piece were two: opus 90 doesn't get played so frequently, other than in complete cycles; and it will be played tomorrow in Perth Concert Hall by the amazing Welsh pianist, Llyr Williams.

Since making the decision, you will know of course that the Edinburgh International Festival programme was launched and, as is the way of coincidences, guess what's going to be played in the Usher Hall series? None other than the Piano Sonata in E minor, opus 90, where it will feature as the opener in an evening recital to be given by the Hungarian-born pianist Andras Schiff, who has recorded all 32 of Beethoven's Piano Sonatas, and who has been doing some interesting work in recent times with another piece by Beethoven. But before the context grows any broader, let's stay focused on opus 90, the point of this column.

Loading article content

What's so special about this sonata? Well, everything, actually. It's an unusual piece in many respects. For a start it stands at a critical point in Beethoven's compositional development. It was written in 1814, and is thus right at the threshold of what tends to be called his "late" period, the astonishing years which gave birth to all those monumental piano sonatas and string quartets between opus 101 and 135. I suspect some might wonder if opus 90 is not, in fact, the first of the sonatas in that mighty handful of works. I don't buy that, but never mind; let's look at opus 90.

It's only got two movements. That's not unique in Beethoven: there are a few other two-movement sonatas, not least the ultimately transcendent final sonata, opus 111, with a fast, dramatic C minor first movement before the composer, in the sublime second movement, set in a plain C major, heads off into visionary spheres. But two-movement sonatas are not the norm.

So what's in these two movements that makes the sonata so unusual and different?

The whole thing lasts only 15 minutes, and Beethoven asks for it to be played "with liveliness and with feeling and expression throughout". The first movement is compact and concentrated, with everything packed into a short space.

For all its "liveliness", which varies in projection from performer to performer, I actually hear it in my head as something more interior, more intimate, as though Beethoven is having some kind of quiet discussion with himself, with an idea and a counter idea, a proposal and a counter proposal. This six-minute debate doesn't get resolved: there's no conclusion, no climax to the discussion; the music doesn't end with an assertion. It simply comes to rest.

And immediately, without pause for breath, the nine-minute second movement begins to flow - and it's incredible.

It is a pure, unbroken arch of lyrical melody. It's one of the longest, most singable and tuneful melodies Beethoven ever wrote. And you know what Beethoven - that consummate delver and developer, who couldn't think of a musical cell or theme without working it to the bone - does with this great, memorable and magical tune? Almost nothing at all.

In a stroke of pure genius he leaves it absolutely alone to sing. It's so exquisite, he simply repeats it. Seven times in succession he repeats it complete, with a wee swapping around towards the end that places the melody in a different register, but with no significant change.

It is pure melody. It is almost Schubert. It's one of the most beautiful things I have heard, and it rings in my mind as I write.

Written in 1814, eh? Happy 200th birthday, opus 90.