Only a few years after their completion, György Ligeti's Études have already become part of the repertory of a great number of pianists, more so than any other contemporary piece. The reasons for this phenomenon can be linked to the "pianisticness" of Ligeti's writing and his fascinating conception of sound, which poses stimulating problems and intellectual paradoxes. In general, all his Études are based on precise geometries, already apparent in the graphics of the score, but even more evident in the movements, often symmetric or specular, that the hands have to make. Moreover, it is often the specific conformation of the keyboard that constitutes a starting point for generating further spatial reciprocities or parallelisms.
The fascinating difficulty of these pieces resides essentially in a sort of labyrinth, resulting from the complex polyphony that automatically arises from the initial geometric plan. It may happen, then, that the pianist's two hands must control four parts, each with different metric connotations and all featuring an intricate play of intersections. In reality, this could be said of any contrapuntal piece. The difference is that in the case of Ligeti the counterpoint generates two very particular phenomena: the no longer convergent relation between what the pianist plays and what he hears, and the consequential, paradoxical coexistence of two (or more) parallel and overlapping sonic worlds, both apparently real and yet different. We are therefore dealing with a counterpoint squared, or rather cubed, in which the superimposition of the parts with different characteristics generates symmetric or spiraliform patterns, or in any case ones that are endowed with particular reiterations, creating singular illusory effects that disorientate the ear of both the player and listener.
From a purely metric point of view, a stimulating antecedent of Ligeti can be found in the writing of late Chopin. A clear example can be seen in measures 175-176 of the Ballade op. 52: here we have three different parts, each with its own different meter, corresponding to the numbers three (middle part), four (upper part) and nine (left hand), considering the triplet sixteenth-note as the unit. The parts finally come together after 36 notes (36 triplet sixteenth-notes, therefore two measures of 6/8), 36 being the lowest common denominator of 3, 4 and 9. Of course (luckily!) performers of Chopin (myself included) don't usually feel it necessary to make such a calculation in order to play this passage appropriately (which, on the contrary, requires an atmosphere that is as suspended and dreamy as possible).
So, one wonders if it is really necessary for a performer of Ligeti's Études to be totally aware of their geometric-polyrhythmic mechanisms. Certainly in many of the Études the poetic interpretation (achieved above all through a free and “inspired” reading) has priority over the mathematical precision of the performance, which among other things would risk limiting the freshness of the phrasing. What is more, it should be noted that, in the experience of performing the Études, it is rarely possible that the pianist could have in mind the metric subdivision written in the score. Ligeti was surely aware of this problem, to the extent that in some specific cases the bar lines have no indicative value in terms of meter or articulation, but are there just to help the pianist “orientate” himself. Furthermore, it is natural for the performer to create his own scheme to facilitate the efficacy of the performance. This scheme might even diverge notably from that of Ligeti, and in any case would never be evident to the listener.
Other interesting reflections arise from a comparison between Ligeti's Études and Conlon Nancarrow's Studies for player piano (the piano roll, predecessor of the modern Yamaha “Disklavier”). It is no chance that Ligeti openly admitted to having gained many of his ideas for the Études from the works of Nancarrow, who composed a large number of pieces for piano roll, not writing on the traditional paper score but directly onto the roll, inscribing on them particular geometrically complex patterns. A fascinating meeting point can be found in the relation between sound and geometry in Ligeti's Études, in which, moreover, the performer takes on a fundamental role. While Nancarrow mistrusted the imperfections and technical limits of the human pianist, preferring the relentless mechanism of the player piano, Ligeti, especially in his first book of Études, purposely exploits the imperfections and "asymmetries" of man's perceptual system and his physical and nervous structure to add an additional value to the already extremely high quality of the written composition. Therefore, while it can be useful for the performer to be aware of the combinatory mechanisms underlying the Études, on the other hand it is important that the pianist should not identify himself too much with a performer-robot like the player piano, otherwise he risks losing certain expressive possibilities (reserved to the imperfect human player) foreseen by Ligeti.
An example of this concept can be found in Étude n. 3, “Touches bloquées”, in which a phenomenon often associated with a serious defect of the piano, that is to say a key that remains depressed and doesn't rise back to its natural position, becomes the nucleus for the creation of a singular play of contrasts between two parallel perceptions of the same music: that of touch, characterized by the blocking of the key (or keys) prescribed in the score, and that of hearing, which perceives a strange faltering rhythm caused by the absence of the note of the blocked key, even though the figuration on paper would appear regular.
This amusing divergence between touch and hearing will, of course, only be perceptible to the performer: his fingers will carry out regular movements, but some of them will suddenly find themselves “with no ground beneath their feet”, just like when you are going down some stairs and you come across steps that are much deeper than the previous ones. The performance is, then, undoubtedly conditioned by this disarrangement, which also the listener clearly notices. One might naturally object that after the first reading of the score the pianist will already know very well which keys are blocked, and so there will be no surprise factor in the performance. This is true. But it is undeniable that the total separation between the movement of the fingers that are reading a regular chromatic scale and the acoustic result deriving from the blocked keys creates an effect that cannot in any way be reproduced with alternative technical solutions. In fact, if Ligeti had written “Gb, F, rest, Eb, rest, Db, rest, B” instead of “Gb, F, E (blocked), Eb, D (blocked), Db, C (blocked), B”, the result would have been another, precisely on account of the different psychological preparation of the pianist in tackling the “gap” made up by the rests: just as if, going back to the paragon with the previously-mentioned stairs, we knew in advance which were the deeper steps, and were thus already prepared for the greater distance that our legs had to travel.
Of course, the idea of blocked keys, and more indirectly of “notes not notes” has very distant origins. While the direct antecedent, as Ligeti himself declares in the score, comes from Henning Siedentopf's essay, “Neue wege der Klaviertechnik” (1973), traces of this conception can already be found in the works of Robert Schumann, in particular in the Abegg Variations op. 1. In the cadence before the last return of the theme, Schumann adopts a writing by subtraction, making the theme emerge not by striking the relative key, but by releasing the others. In fact, he prescribes releasing the keys of the chord made up of all the notes of the theme (A, Bb, E, G, G) one at a time, starting from the lowest, thus allowing the resonance to emerge of the note that is in turn “exposed”. But when the moment to replay the last G of the theme arrives, Schumann comes up against a paradox: releasing the very key that is supposed to keep sounding, in other words removing the sound from the very note that is to remain audible. Like saying: 1 - 1 = 1. And yet he gets round the problem in exemplary fashion by means of two singular devices, which in some way anticipate the aesthetics of Ligeti. The first consists of the accent on the second G.. There are also accents on the previous notes of the theme (though always held notes), but in this case the accent is doubly utopian, being actually placed on the second part of a held note, with no other notes being present. The second device, consequential to the above-mentioned accent, of which in practice it represents the heterodox realization, involves the sustaining pedal which Schumann indicates should be lowered in conjunction with the utopian repetition of the G. In so doing the resonance of the same G is increased (possibly together with a percussive “thump” that the pianist could give with a deliberately exaggerated pressure on the pedal), but more especially the pianist (and the reader of the score: a little less so the simple listener) is helped to imagine a note that is otherwise impossible and beyond any earthly logic. The interesting aspect of this singular solution lies in the divergence that is created between the four parallel sonic conceptions of the same note: the G imagined by Schumann, the G written in the score, the G played by the pianist and the G perceived by the listener.
Schumann once more approaches “pianistic utopias” and impossible notes in the Humoreske op. 20, more precisely in the “Hastig” episode, in which the middle part has the eloquent epithet “Innere Stimme”: it is, in fact, a melodic line written in the score, not to be played by the performer but just read and experienced inwardly, without the need for any parallel acoustic perception. This episode is subsequently repeated unvaried, except for the part that is not played. The concept of Innere Stimme is certainly very close to the experiences encountered by the performer when tackling Ligeti's Études, although there is a fundamental difference that needs to be underlined. In practice, the performer of the Humoreske finds himself producing (and communicating to the listener) a line that is written in the score without being able to play it, whereas the performer of Ligeti's Études finds himself communicating parts and rhythmic modules that he doesn't know he is playing, since they are triggered automatically by the superimposition of other elements that the performer is not called upon to control.
Finally, it should be said that it is precisely this relationship with the uncontrollable and with “negative” sound (in the photographic sense of the term) that represents the most innovative and, paradoxically, most “pianistic” aspect of Ligeti's Études. And this is the very reason why his Études have opened the way to many further possible developments in piano language that have yet to be completely explored.