The conventional understanding of Western classical music is that it evolved like an organism: slowly, through a series of infinitesimal, incremental changes, without any unexpected leaps. The basic tonal system that emerged in the early Renaissance period was tweaked and passed on by each generation of composers, transforming, over the course of several centuries, the fairly plain harmony of Monteverdi and Byrd into the dense, cat’s cradle chords of Wagner and Strauss. For any individual composer, his or her creative horizons were largely defined by the “progress” that had been made up to that point: there would have been simply no way for the prim Mozart, for instance, to imagine the rich, romantic harmonies that would become the norm a century after his death.

The romanticised image of a tortured genius was popularised at the beginning of the twentieth century

Except he did. The opening bars of Mozart’s String Quartet No. 19 — later nicknamed the “Dissonance Quartet” — could easily be mistaken for Schumann or Brahms. The piece mystified Mozart’s contemporaries — one of its more generous critics called it “too highly seasoned” — and it continues to perplex us, for different reasons, today: how did Mozart anticipate, so far in advance, and for just those few bars, the full-bodied chords of the Romantics? All evidence suggests that listeners of the eighteenth century found the quartet as impenetrable as the average listener today finds, say, Boulez: at least a couple of learned commentators concluded at the time that the score must simply have been riddled with mistakes. And yet the supposed “dissonance” sounds entirely natural to us today: far from being a crazed foray into unknown harmonic territory, it’s as though Mozart was given, by some rupture of spacetime, a momentary, perfectly-formed glimpse of the future — before, all of a sudden, in bar 23, resuming normal decorous service once again.

Mozart was not actually alone in departing from the expectations of his time: listen, for instance, to the terrifying opening chord of “Les Élémens” by (the aptly named) Jean-Féry Rebel (1737) or Heinrich Biber’s “Battalia” (1673). But two composers in particular stand out for what we might call their harmonic prophecy: Carlo Gesualdo and Anton Reicha.

Gesualdo (1566-1613) was an Italian prince and composer whose daring chromatic shifts remained unmatched until the middle of the nineteenth century. Reicha (1770-1836) was a Czech composer and theorist, contemporary and friend of Beethoven, whose 36 Fugues are an anthology of experimentation — the skittish Fugue no. 12, for instance, could easily be mistaken for one of Conlon Nancarrow’s works for player piano 150 years later.

How and why were these composers so ahead of their time? Much has been made of Gesualdo’s catastrophic personal life: he was racked with guilt after brutally murdering his wife and her lover, and it has often been suggested that, in his ensuing madness, he dispensed with the norms of his time and used music simply as a personal means of expressing his anguish. This romanticised image of a tortured genius was popularised by a number of composers at the beginning of the twentieth century, among them Igor Stravinsky and Peter Warlock (who some even say committed suicide after coming to believe he was Gesualdo himself). As one of the talking heads in “Death For Five Voices” — a 1995 Werner Herzog documentary on Gesualdo — put it:

He was an artist of the greatest distinction. In fact, we can detect a certain element of genius in him. This, of course, allowed him to anticipate an artistic movement that emerged at the beginning of this [twentieth] century: expressionism. As a matter of fact, he was able to express, using the art form that came most naturally to him, the madrigal, his inner world in its entirety — his solitary and tormented world.

You cannot simply change the emotional meaningof a major chord into a minor chord and vice versa

But what nobody seems quite to confront — perhaps because the implications are unsettling for a materialist age — is just how strange it is that Gesualdo’s personal form of expression should have ended up sounding so eerily similar to the Romantic harmonic idiom that arose, quite independently, several centuries later. In Herzog’s documentary, comparisons are repeatedly drawn between Gesualdo’s music and that of Bruckner, Strauss and Wagner — but these similarities are always presented as mere coincidences: the emphasis is always on Gesualdo’s warped genius, not what any resemblance might tell us about, say, the underlying nature of tonality itself. But is it not possible that Gesualdo actually foresaw the kind of harmonic direction composers might one day take? Could it not be that these future harmonic developments were always coiled up in tonality from the beginning, just waiting to blossom, and that Gesualdo — and Mozart and Reicha — simply had the intuitive ability to realise their logical inevitability from the outset?

Think of music, for a moment, as a language. If the arrival of the strained chords of Wagner or Strauss did not exactly represent an entirely new “vocabulary”, it certainly did represent an evolution of the musical lexicon: similar to the way the Old English word “eald” became “old” in Modern English, or “brodor” became “brother” — or the way ancient terms took on new meanings, like “wench”, which used simply to mean a female child, coming to mean a whore. Well, how would we react if we discovered a Medieval poet who, upon going mad, had started writing in an idiom that turned out to be uncannily similar to, say, modern day slang?

If the analogy doesn’t entirely hold, it’s because we recognise, intuitively, that there’s something fixed about tonality: that it functions like a system of grammar or logic — the rules of which never change — rather than a fleeting, surface level set of vocabulary. We know, for instance — and recent psychological studies back this up — that you cannot simply change the emotional meaning of a major chord into a minor chord and vice versa, whereas you can, of course, easily change the meaning of a word: “brat” means brother in Russian, and a spoiled child in English. What the discoveries of Gesualdo, Mozart and Reicha suggest, then, is that this underlying musical grammar extends far beyond basic features of tonality like major and minor, such that even the subtlest shades of complex harmony have some kind of a permanent meaning — one that made intuitive sense to prescient composers long before they became the cultural norm.

In this sense, their insights were somewhat like Einstein’s ability to intuit purely theoretical claims about the universe many years before they could be “proven” with empirical tests — dipping through the secret passage that connects a genius’s mind to reality, they discovered permanent truths that transcended the historical limitations of their times.

Gesualdo, Mozart and Reicha appear to undermine the modernist charge

This is an unpalatable thought for many. These days, we distrust any aspect of human experience that cannot be explained in purely evolutionary or sociological terms. The linear narrative of music history I mentioned earlier was especially popular among the modernists of the early twentieth century, who, in their nihilistic desire to overturn everything they’d inherited, dismissed tonality, as with so much else humans had once considered valuable, as an arbitrary creation: a language whose meaning had been built up piecemeal over time — but one that could, in principle, be replaced with any other. Schoenberg, for instance, tried to show that it was “exhausted”, and that a “hierarchy-free” twelve-tone system could be installed in its place. Others, like the maverick Harry Partch, dispensed with it altogether and created entirely new systems of tonality (including one in which the octave was divided into 43 notes).

But Gesualdo, Mozart and Reicha appear to undermine the modernist charge. Their ability to predict musical developments far in advance suggests that stylistic differences between eras — between, say, Romantic harmony and Baroque harmony — were not simply “fashions”, accessible only to those familiar with the idioms of a particular moment in time, but different expressions of a single underlying logic, not unlike Chomskian linguistics, the extended possibilities of which were always there from the start. In this sense, our understanding of tonality seems indeed to be an accumulative form of knowledge: the expanded harmonies of the nineteenth century did not “erase” or render meaningless the harmonies of the sixteenth century any more than the discovery that nihonium has 113 protons overwrites the discovery that hydrogen has just one.

Of course, many composers did, under the pressure of their audiences and patrons, restrict themselves to the particular styles of their times. And yes, it does, inevitably, take most people a certain amount of time to make full sense of new and unfamiliar styles. But we make a big mistake if we conclude from this that tonality itself is wholly arbitrary — after all, just because it takes most people a long time to develop a proper understanding of complex mathematical concepts, it doesn’t follow that those concepts are mere social constructs.

There’s something fundamentally irrefutable about the music experience that gives us a glimpse of the transcendent

These days, having survived the scorched-earth modernists, tonality is challenged from a slightly different angle: the assumption that we can explain it in strictly biological or psychological terms instead. But this seems just as crude. Indeed, there’s something rather comical about the attempts of music psychologists in particular — working with the assumption up front that music must be explicable in cold, scientific terms — resorting to the most absurd of explanations. One, for instance, is that minor harmony “sounds sad” because we encounter it less often than major harmony, and we therefore associate it with “less common” emotional experiences like grief and panic — another claims that minor harmony “sounds sad” because some of the notes in the minor scale are lower than the ear expects, and that we subconsciously translate this “lowering of expectations” into a negative emotional experience.

Of course, if you start from the assumption that all phenomena in the world are meaningless mechanistic physical things, or arbitrary human creations, then you’ll only ever reach certain kinds of conclusions. But the mystery of tonality strikes me as one area where the strict materialists (and philosophical modernists) are forced to do some really rather remarkable mental gymnastics.

Either way, nearly half a millennium after Gesualdo’s experiments, tonality lives on today as healthy as ever: in pop music, jazz, soundtracks, and even, once again, in some contemporary classical music. And having now survived this far, is it not reasonable to wonder if our forebears, who believed tonality spoke to something fundamental about our place in the universe, were actually right? At a time when we’ve lost faith in almost everything else, it certainly seems to me that there’s something fundamentally irrefutable about the music experience that gives us a glimpse, however indirect, of the transcendent.