In previous posts I have argued that Rachmaninoff, the self-proclaimed musical conservative, was not only influenced by his more forward-looking contemporaries, but actually incorporated some of their modern harmonic devices in his music. Polytonality is the use of two different keys at once. The classic (but not earliest) example is from Stravinsky’s Petrushka:
Although there are somewhat tortured harmonic theories to explain this chord in a single tonality, it is simpler to consider this as simultaneous C major and F# major chords, keys a tritone apart. On the piano (which is the instrument this is played on in Stravinsky’s ballet) this tremolo consists of two simple but unrelated chords, one all white keys and one all black keys. Tonality is ambiguous. Is the key here C or F#?
Certainly Rachmaninoff was not so extreme in his harmony!? He comes close to the same kind of tonal ambiguity here in the 23rd variation of the Rhapsody on a Theme of Paganini:
Here the piano is playing in A flat minor, while the orchestra plays in A minor, a half tone higher. It’s an effect suggesting that the piano is out of tune, i.e. too flat. Perhaps this is a little joke (there is a lot of humor in this piece) on violinists playing out of tune. The Rhapsody includes many violin-like effects, as the theme of the Rhapsody was written by Paganini, the greatest 19th century violinist. In the last variation, which mimics the leaps seen in virtuoso violin pieces, Rachmaninoff uses polytonic arpeggios in the left hand which could have come right out of Petrushka.
The first 6 notes in the left hand of each measure consist of two triads, minor and major, a major second distant. He combines D minor and E major, then E minor and F# major, then F# minor and A flat major, and then A flat minor and B flat major, in a rising sequence. On the third beat of each measure, the chord of the first beat is lowered a half tone (e.g. D minor becomes C# major), to make the tonality even more loose. This is decidedly odd harmony, especially combined with a violin-like right hand of simultaneously ascending and descending chromatic scales.
These examples and my previous post on this subject demonstrate that, as much as Rachmaninoff professed publicly that he was incapable of understanding “modern music,” he was very capable of using very modern harmonic idioms in his own music when it suited him.