In the early part of the 20th century, there were two musical revolutions going on either side of the Atlantic. At the time Schoenberg and the Second Viennese School were creating their own shock waves, Charles Ives was quietly creating all sorts of musical breakthroughs, almost unnoticed in his native New England.

Schoenberg felt that the excesses of romanticism and chromaticism had reached their peak with Wagner, Mahler and Richard Strauss and that there was nowhere left to go, so the next logical step was to develop a new atonal language, free from hummable tunes, regular beats and familiar harmonies, and with a new intense expressionism ripe for a new era. From this point onwards, things would never be the same again. Piano music changed forever, and certain milestone solo piano works from the biggest names in modernism and 20th century contemporary music help to chart the course of each of these mini-revolutions over the next 100 years.

Schoenberg’s Three Piano Pieces, Op.11, written in 1909, was the first work to hit the scene fully exploring this new atonal language, with the last semblances of tonality now just the merest hint. He had not yet developed his twelve-tone method, and this work was really the beginning of a gradual development towards serialism, with his Suite for Piano of 1925 being his first piano piece to be written using twelve-tone rows throughout. Schoenberg’s leaner, more concise style was also a hallmark of Anton Webern, whose only solo piano work, Variations for Piano, is a finely honed culmination of all of these techniques where every wisp, violent gesture and moment of silence is carefully placed to create a concentrated, highly expressive piece in perfect miniature.

Meanwhile, Ives had written his pianistic masterpiece, the “Concord” Sonata, quite independently of the musical innovations occurring in Europe, although it was not to become influential until long after it was written. Composed originally between 1911 and 1915, Ives’ “impression of the spirit of transcendentalism” drew together many intriguing and experimental elements.  In the second movement he gives the instruction to depress the keys using a plank of wood (although the forearm would do), and he litters the piece with cluster chords, complex harmonies and rhythmic structures, as well as his characteristic use of hymns, popular and marching band tunes phasing in and out. Even the beginning of Beethoven’s Fifth Symphony makes a conspicuous appearance. Tension, nostalgia, humour and philosophical reflection are all dyed into the fabric of the piece, but for all of this musical invention, Ives’ music was not heard much during his lifetime, although as his reputation grew, people like Stravinsky declared Ives as “the Great Anticipator”, with Schoenberg also writing “There is a Great Man living in this country....His name is Ives.”

In the 1930s, Olivier Messiaen was starting to develop his own new musical language outside normal western conventions. Although he did dabble in serial techniques and taught the twelve-tone system of Schoenberg to his pupils, he did not major in writing serial music in the strict sense. Vingt regards sur l’enfant-Jésus (twenty contemplations on the infant Jesus) is one of a large number of solo piano works written by Messiaen. Being a devout Catholic, this colossal piece (roughly two hours long), written in 1944, uses religious themes such as God, mystical love, the star and the cross. Dynamic, chromatic and ecstatic, it captures his unique style by taking inspiration from numerous artistic images as well as from birdsong, a key influence throughout his career (birds were, after all, “the first to make music on this planet”), and his characteristic use of colours – he saw colours when he heard sounds, so this became central to his compositional thinking.

Meanwhile, Pierre Boulez, a former student of Messiaen, was boldly declaring that anyone not working with serialism was “useless”. He then went one step further in his 1952 article “Schoenberg is Dead”, criticising Schoenberg for clinging onto traditional forms. Boulez simply regarded a clean break as necessary for the new epoch, with his development of “total serialism” paving the way. His Piano Sonata no. 2 of 1948 puts down a clear and emphatic marker of this dogma in a dynamic, violent and exciting piece demanding great virtuosity. Crushing the classic forms of the past and stretching serialism to its limits, Boulez introduces extreme energy and physicality in order to emphasise the point. The final passage of the Sonata sounds like a lament, but whether it is last goodbye to the past or a signal for the uncertainty of the future, its ambiguity makes it one of Boulez’ most sublime and captivating moments. This significant piece is not for the faint-hearted, but its message is undeniably audacious.

It was round about this time that Boulez met John Cage and Karlheinz Stockhausen, another of Messiaen’s students. Together, their music pushed the boundaries even further, where sound and silence took on new roles. They also experimented with “chance” music, where to varying degrees either the compositional processes or the performances themselves were dictated by random choice. Stockhausen’s first 11 Klavierstücke, written in 1952-56, are landmark pieces.  By this time, he had fully embraced serialism as a way of constructing his own complex systems, and also developed a style whereby performers themselves could dictate the flow of the piece, which he described as “polyvalent”. All of Stockhausen’s new techniques are seen in his Klavierstücke. Boulez took a great interest in these pieces and reportedly sent John Cage a copy of the ending of Klavierstück IV.

Cage was another great admirer of Schoenberg, having studied under him for a while. Schoenberg in turn considered Cage a genius, but as an inventor rather than a composer – he will be remembered most for creating the controversial 4’33”, which requires the performer simply to play nothing so that listeners can absorb the sounds of their environment. One of Cage's most highly regarded achievements is the set of Sonatas and Interludes for prepared piano, written in 1946-48, in which his fascination with percussion timbres and Indian philosophy led him to create a Gamelan-like sound by “preparing” or distorting the sound of certain notes with screws, bolts, pieces of plastic and rubber placed in or between the strings.

The young Elliott Carter had attended the second performance of Ives’ Concord Sonata back in 1939. Carter’s brand of atonal music had a similar rhythmic complexity to that of his peers, but one in which serialism did not feature. Instead, he created numerous different types of compositional structure and used devices like the “all-interval” chord to create organised pitch patterns. His 1980 piece Night Fantasies was the first he wrote for solo piano since his very fine Piano Sonata of 1945-46. You could sit for hours pondering over the way Night Fantasies was constructed: the opening passage being characterised by an all-interval chord, along with its inversion, within a two-stream underlying polyrhythm where the faster stream pulsation recurs every 35 sixteenths and the slower stream recurs every 27 quintuplet eighths, etc. But it is perhaps best left to the composer himself to describe this evocative piece in much more straightforward language: “a piano piece of continuously changing moods, suggesting the fleeting thoughts and feelings that pass through the mind during a period of wakefulness at night.”

György Ligeti makes up this dream team of 20th century modernist luminaries with his 18 Études for solo piano. Written between 1985 and 2001, this collection provides one of the most comprehensive contemporary piano explorations of the last century. They combine an enormous variety of technical content, requiring great virtuosity, with an endless supply of expressive ideas. The opening Étude No.1 (Désordre) sets the scene, with its polyrhythms and its unsettled and ambiguous tonality where one hand plays the white keys and the other hand plays the black keys to create a curious diatonic and pentatonic mix. The first three Études were dedicated to Boulez, but any one of the whole cycle can be picked out as a highlight. Try listening, for example, to the contrast between the serenity of “White on White” (No.15) and the endless driving ascents of “The Devil’s Staircase” (ominously placed at No.13), which also includes one of the most extreme dynamic markings in any score, “ffffffff” (yes, that’s eight fortes!).

With so much to challenge us in these inventively rich and uncompromising pieces, we can be sure that for as long as we continue to have pioneering composers like this, music will never stand still.