You have already recorded the Klavierstücke VII to XI. Now I to V will follow. What fascinates you about this cycle?

What fascinates me about the cycle of piano pieces is that it was written in a compositionally very exciting and open period, in which the composers of serialism in the 1950s developed their very own musical language in an experimental openness on a voyage of discovery into the new and unknown. I am very enthusiastic about the fact that Stockhausen found a personal and unmistakable tonal language, and in the course of the cycle, the individuality of it emerges more and more clearly. It begins with the first pieces, which very radically break down the music to its basic parameters of pitch, tone duration and intensity. Subsequently, individual tones or tone points are grouped together and thus gradually arranged in ever-increasing complexity until, from Klavierstück VII onwards, very special tonalities with beautiful harmonics come to the fore. Also very special is the insane and highly virtuosic use of clusters in Klavierstück X, which is without antecedent, makes the piano sound in a unique way and lets the performer experience such a physically new playing situation with the instrument that it is a real joy.

Even today, almost 60 years after they were written and 25 years after I began my personal involvement with them, I hear these pieces as unbrokenly modern, fresh and full of vitality. Especially the curiosity for the unknown and the unexpected beauties that emerge during this search inspire me again and again. For me personally, the cycle of Stockhausen’s piano pieces is one of the milestones of the 20th century repertoire.

Karlheinz Stockhausen wrote the piano pieces over a period of more than 50 years. Would you still say that they are a coherent cycle? What connects the pieces?

Stockhausen composed his piano pieces over this large period of time, if you include the Klavierstücke XII – XIX, which are from the opera cycle “LICHT”, and the cycle “NATÜRLICHE DAUERN”. Not all of these piano pieces were intended by him as a unified cycle. However, some elements connect these pieces, for example:

– the architectural approach to the musical form

– the inner peace of allowing very long reverberations and pauses

– a specific form of affinity to the piano sound

– a quasi physical-acoustic-scientific analysis of sound through composition

– a clear and cheerful atmosphere through and through

– a pianistically conceived sound language that makes playing the pieces very natural from an instrumental-technical point of view.

The pieces that I recorded for the label, i.e. pieces I to XI, were actually conceived as a cycle from the beginning. They all share the same sound language and use the same constructive techniques when composing. Without wanting to go too far, one can say in brief that very many elements of the compositions are controlled by series of numbers from 1 to 6, arranged in magic squares.

Stockhausen has spoken of the piano pieces as “my drawings”. Can they be recognised as sketches or studies in other, larger-scale works?

I have always understood the term “my drawings” for the piano pieces in such a way that Stockhausen wanted to say that in them one can perceive his music as reduced to the core, and in this reduction of means, as through a burning glass, the decisive intentions can perhaps even be perceived more clearly. The same musical principles can be found in the electronic pieces, the chamber music and orchestral works; the pieces from this period were all written with the same compositional technique, only here everything sounds more opulent and richer. Just as in painting, comparably, you would see the difference between a pencil drawing and a coloured oil painting.

You worked with Stockhausen for many years. How did you feel about the collaboration? Did you also work on the piano pieces?

As a young student, I was deeply impressed by several concerts with musicians who had worked intensively with Karlheinz Stockhausen. The appropriation of the compositions down to the last detail, the rote playing of these modern and complicated scores, the total internalisation of the musical text and the dedication in playing, stood out for me clearly and refreshingly from other concerts of contemporary music that I heard at the time. Over time, I developed an ever more urgent desire to get to the bottom of the secret of these intensive interpretations, and possibly to follow my own path in this direction. From 1998 onwards, I fortunately had the opportunity to come into direct contact with Stockhausen through the Stockhausen courses in Kürten, and subsequently a personal collaboration developed to which I owe an enormous amount of impetus for my further musical development and artistic formation. We worked together on many premieres of new works and, in addition to the works “Kontakte” and “Mantra”, we also spent countless hours in rehearsals and performances of the Klavierstücke. Stockhausen, on the one hand, was able to show by his own example how precisely he could both imagine and audibly control tempos, volumes, articulations, etc. If he wrote the tempo eighths equals 40 in a piece, then he wanted to hear exactly this tempo and no other, and could effortlessly audition it immediately in the correct tempo in the rehearsal, and point out to the player his deviation (faster or slower tempo). On the other hand, he was able to enable the musicians working with him to acquire precisely these skills of precision and control through his meticulous method of working, which never diminished in its intensity and unconditionality.