The first years of the 19th century found Beethoven at a crucial point of transition in his career. Having mastered the Viennese high Classical style for which Haydn and Mozart served as paradigms, he sought to break free of his past. According to his pupil Carl Czerny, Beethoven told his friend Wenzel Krumpholz, ‘I am only a little satisfied with my previous works. From today I will take a new path.’ This ‘new path’ arguably reached its apex among Beethoven’s piano sonatas in No 23 in F minor, the Appassionata, in which the music’s stormy temper and defiant, fist-to-the-sky qualities virtually define Beethoven’s middle, ‘heroic’ period. By cannily deploying the keyboard’s full registral scope, Beethoven conjures up sonorities that have orchestral impact, yet are quintessentially pianistic, like the opening movement’s fiery arpeggiated chords and the finale’s relentless rapid figurations. As such, much of the piano-writing actually ‘feels’ under a pianist’s fingers in the same way that it ‘sounds’ to the listening audience.

Speaking with Mariam Batsashvili over the phone, I ask if she feels that the music’s tactile immediacy either stems from Beethoven’s fondness for improvisation or represents a kind of compensation related to the deterioration of his hearing. ‘I feel that it’s mainly a matter of emotion,’ she replies. ‘The music is constantly moving, and asking for one’s attention. There is not one moment of boredom, and the wide contrasts in mood are very relatable to real life. And whether one is playing the Appassionata or listening to it, the piece triggers emotions that one cannot always express in words or actions, or it conjures up feelings within a person which are often repressed.’

Batsashvili’s relationship with the Appassionata dates back to her formative years. ‘I first learnt it when I was either 14 or 15 years old. I worked on it with my Georgian teacher Natalia Natsvlishvili. She was not so much a performing pianist as a teacher, primarily, but to me she remains the greatest musician I’ve ever known. Her knowledge of interpretation and of understanding pieces and delivering this to her students was absolutely sensational. She assigned the Appassionata to me because she thought it could be “my piece”. But she said that I should not hear it played by anyone on a recording until I learnt it myself.

‘What’s remarkable’, she continues, ‘is that almost everything in this sonata comes out of the motifs presented in the opening movement’s first 13 bars: that simple spread-out minor triad, the trill and that four-note pattern with the three repeated notes. But while the basic material is established in the opening bars, it also gives a sense that one is searching for something. I’m thinking about when Beethoven repeats the F minor motif a half-tone up in G flat major. So even if the ideas are fully formed, they should sound as if one is creating the music spontaneously.’

Jumping ahead to the theme and variations that make up the central Andante con moto movement, we talk about the question of tempo relationships. Should there be strict metrical correspondence between the variations, or can the player be relatively free? Batsashvili admits to having struggled with this issue a little bit. ‘At first, I tried playing the whole movement with a metronome, experimenting with steady and consistent tempos. Yet somehow that music felt locked in, either feeling too fast or too slow; or else there wasn’t a sense of the music moving forwards in a natural way. So in my recording I do make adjustments in tempo between the variations, but I try to do that in a subtle way. What’s important for the interpreter is to find the right balance between the theme statements and the accompaniments.’

She continues: ‘But look how Beethoven resolves the movement – not on a concluding tonic chord, but on an ambiguous diminished chord. This one chord in itself is a point of transition between the second movement and the finale. It represents uncertainty. As you’re listening to this beautiful movement, or playing it, you think that you are on top of the world, and you feel very peaceful and balanced; yet when that arpeggiated diminished chord appears at the very end, it quietly upsets your balance. I think I related quite strongly to this movement when I was a teenager, because although many things were going well for me, there always were moments of doubt, moments of questioning. By the way, I find the demisemiquaver variation to be the most challenging part of this sonata from a technical standpoint. I have to work hard to keep these notes in perspective so that they don’t disturb the melody, or so they don’t become too loud or too present.’

Batsashvili also cautions against launching into the finale too briskly. ‘It’s a big temptation to race through the music, but you have to remember that Beethoven marks it Allegro ma non troppo. Besides, with this almost constant texture of busy semiquavers, the music is going to sound fast anyway. This helps you really build towards the Presto coda.’ As for generating excitement in the coda without sounding vulgar, Batsashvili reminds pianists that Beethoven marks it Presto – not ‘Prestissimo’.

I also ask Batsashvili about two other textual points in the finale which remain subject to debate. ‘Ten bars before the end in the left hand, I prefer F natural in the bass, because it reinforces the tension in the concluding downward right-hand arpeggios more definitively than the A flat that Vladimir Horowitz famously played. And it goes without saying that I take the repeat, even though many pianists of the past didn’t do so. I think you need it, because otherwise the movement feels too short.’

Although Batsashvili acknowledges that a studio recording often represents an idealised live performance, her approach to tackling the Appassionata was to ask her producer to record in long, uninterrupted takes. ‘I wanted the atmosphere to be as concert-like and improvisatory as possible, so I asked a friend of mine to come to the sessions and I went through the whole piece for them, as if I was playing in a concert – without stopping, from the beginning to the end. I played the whole sonata about four or five times all the way through, and from these long takes we selected what I thought was best.’

The process did not, however, preclude the pianist’s scrupulous adherence to Beethoven’s trademark subito dynamics, phrasings and pedal indications. ‘This is the imprint of Natalia Natsvlishvili. She always told me that as soon as you have learnt all of the notes, all of the dynamics, all of the expressive indications, that’s when you can start thinking about Beethoven’s indications as your own ideas, as if they’re coming from you. Of course, Beethoven knows better than you, but the point is that you are channelling Beethoven through yourself. You are the vessel that conveys his ideas to the public, yet you internalise his ideas. For me, this is the real meaning of interpretative freedom.’