Musical keys: what they are, the different keys and how they are used in classical music

What is a musical key?

Every piece of music – be it a pop or folk song, a string quartet, a violin concerto or a operatic overture – is in a certain key. But what do we mean by this? Let’s first look briefly at what a key is.

Essentially, a key is the principal group of notes that gives any piece of music its harmonic building blocks. The main notes used in a song are usually all from one particular scale, and this is where we name the song’s key from.

The key that most music learners come across first is the key of C major. That’s because the scale of C major uses no sharp or flat notes – it simply goes C, D, E, F, G, A, B, C. That means no need to use the black notes on the keyboard – only the white ones.

What is… tonality?

A song that only uses notes from the C major scale will (usually) be in the key of C major.

In fact, each key signature (in this case, no sharps or flats) is shared by two keys: one major, one minor. C major shares its key signature with A minor.

But there are plenty more keys than these two. And different keys seem to have different characteristics, so that a composer is likely to choose a different key for writing a piece of joyous or festive music, than for something a little more melancholy or otherworldly.

Let's take a look at some of the most common keys and their sonic attributes or moods.

How did composers use different musical keys?

For centuries, people have claimed that musical keys have special qualities of their own. In the Baroque era, whole treatises were written on the subject. It’s been said that E flat major is warm, D flat major is spooky, and E flat minor is seriously unhinged.

Keys have colours too, apparently: E major has been described as sapphire blue, A flat major as purple, and D major as golden. Composers and performers who experience the condition of synaesthesia will understand this well.

All hokum, say the sceptics. They’ll point out that for every person who thinks C major is chalky white, there’ll be another for whom it’s emerald green. They’ll remind us that though keys may have had distinct ‘colours’ in the era before Bach, when odd, exotic tunings abounded, every major and minor key now sounds – thanks to equal temperament – absolutely identical to every other.

As for the expressive qualities of keys, these vary hugely from one composer to the next. F sharp major had a special significance for Scriabin, C minor had a special flavour for Beethoven. But F sharp major sounds very different in Tchaikovsky and Bach, and Shostakovich’s C minor isn’t like Beethoven’s.

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All this is undeniable, but it’s not the whole story. The fact that earlier composers thought of keys in specific ways surely affected the way they composed in them. And if we think of G minor as tragic largely because Mozart had a special feeling for that key, isn’t that enough? Won’t that affect the way we hear that key in other contexts?

It’s true that our feeling for the qualities of keys, once so sharp, has been blunted. But let’s not reject those qualities just because their oddity doesn’t fit our conformist age. Let’s cherish them for their quirkiness, and the enticing flavour they bring of a vanished world of feeling. Here are ten of the most characterful keys in Western music…

The different musical keys and their use in classical music

C major

This is where things begin, in two senses. It’s the simplest key, the one with no sharps or flats. And it’s also the key in which the child’s fingers take their first faltering steps on the keyboard. Perhaps that’s why it’s associated with a certain child-like simplicity.

The first Prelude from Book One of Bach’s Well-Tempered Clavier has this quality, in a completely unself-conscious way, and Debussy’s ‘Dr Gradus ad Parnassum’ from Children’s Corner has it too – though now the innocence is very self-conscious indeed. Because of its primal simplicity, the key has a grounded feeling, optimistic and solid.

Think of the unarguable certainty of Mozart’s great C major works such as the late String Quintet, and the ‘Jupiter’ Symphony. Or the way the Representation of Chaos in Haydn’s Creation leads, with a feeling of utter inevitability, to a great blazing C major affirmation on the words ‘And there was LIGHT.’

E minor

‘Effeminate, amorous, plaintive,’ said French Baroque theorist and composer Marc-Antoine Charpentier of this key in 1682. ‘Grief, mournfulness and restlessness,’ said the great physicist and acoustician Helmholtz in 1863. Well, as the old Jewish proverb says, ‘two of a trade will never agree’, and that’s as true of key theorists as it is of carpenters.

Helmholtz seems to be closer to the general view of E minor, though that may be because he lived in the same era as the composer who fixed them indelibly: Johannes Brahms. His E minor Cello Sonata and Fourth Symphony both have those qualities, though with an admixture of tragic fatefulness.

Elgar’s Cello Concerto fits Helmholtz’s description even better, as does Rachmaninov’s Symphony No. 2.

Heavy metal and flamenco guitarists love it too, as it sounds richly sonorous on the guitar, and sits comfortably under the hand.

A major

In Christian Schubart’s Thoughts on Musical Aesthetics of 1806, this key gets the most elaborate CV. It’s just the ticket for ‘declarations of innocent love, satisfaction with one’s state of affairs; hope of seeing one’s beloved again when parting; youthfulness and trust in God.’

Thank goodness pieces in A major aren’t usually so pure of heart, but nevertheless an innocent, radiant quality does cling to many chamber and orchestral pieces in this key, perhaps because the key sounds especially glowing on stringed instruments.

You hear that quality in Dvořák’s lovely String Sextet and Schubert’s ‘Trout’ Quintet. It’s also there in Mozart’s Piano Concerto K488 and, above all, in his Clarinet Quintet.

The piece that reveals this quality best is the Prelude to Wagner’s Lohengrin, which for the first few bars is nothing but high A major chords, dazzling like shafts of sunlight.

F major

The great musical essayist Donald Tovey speculated that keys get their colour and quality from their relationship to the simplest key of C major. The closer to C, the more straightforward and brighter is the key’s emotional colour; the further away, the more strained it becomes.

It’s easy to punch holes in Tovey’s theory, but it is certainly true that F major – one of the keys closest to C – is sunny, stable and cheerful. But it also has connotations of the pastoral and of hunting, largely because horns – most of the time – are pitched in F.

The bucolic horns in the second Trio of Bach’s Brandenburg Concerto No. 1 encapsulate this feeling, as does the horn call that ushers in the last movement of Beethoven’s ‘Pastoral’ Symphony. Handel’s music is full of horn-drenched F major outdoors feeling; the first Water Music suite is a good example.

G Minor

Several keys have a strong association with a particular composer. C minor was Beethoven’s ‘stormy’ key, and Scriabin had a fascination for the magical sound of F sharp. But no key bears the stamp of one composer as vividly as G minor, which Mozart reserved for his most tragic utterances.

Perfect examples of the inconsolable desolation he finds in this key are in the Magic Flute (Pamina’s great aria of loss ‘Ah, ich fühl’s’), the late G minor String Quintet, and Symphony No. 40.

Other composers find a similar depth in G minor, including Verdi, much of whose astonishing Requiem is in that key. Bach’s Solo Violin Sonata No. 1 and Bruch’s Violin Concerto No. 1 create an association between mournful G minor and the sound of the violin’s bottom string. Like all these associations between key and instrumental sound, this one spreads beyond its source, colouring the way we feel about the key as a whole.

D major

This is the key of festivity and joy par excellence. One reason is that it is on the so-called ‘sharp’ side of C major. Keys are best imagined as disposed around a circle; beginning at C major, one can either travel round sharpwards, visiting keys with increasing numbers of sharps in the key signature. Or one can travel ‘flatwards’, via keys with increasing numbers of flats in the key signature.

Major keys with sharps tend to be increasingly bright and energised, and D major has two. Another reason D major feels festive is that it is a bright sonorous key for violins. Several well-known violin concertos are in D major, including those by Beethoven, Tchaikovsky and Stravinsky.

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Trumpets in Baroque times were often pitched in D, and Baroque music is full of D major violin-and-trumpets joy; examples in Bach include the Magnificat and the Brandenburg Concerto No. 5.

D minor

D major is one of the brightest and most festive keys; convert it into D minor, and it becomes severe and stark and awe-inspiring. Interestingly, this quality is rooted in the very same martial, brassy valour that makes much D major music so festive.

Take the Nelson Mass, surely the most severe and granitic of Haydn’s late Masses. Aren’t those qualities bound up with the minatory sound of the trumpet, rat-tat-tatting away in martial fashion at the beginning? The implacable, titanic feeling found there recurs in later D minor pieces, such as Beethoven’s and Bruckner’s Ninth Symphonies and Mahler’s First.

However this colour isn’t found in every piece of D minor sternness. Bach’s Art of Fugue is abstract in sound, and yet its austere, grave beauty seems very rooted in its key. Mozart’s D minor has a demonic quality all of its own, revealed best of all in his opera Don Giovanni.

E flat major

Moving round the circle of keys in a sharp direction produces increasing brightness, energy and tension. Moving in a flatwards direction has a sense of increasing relaxation and spaciousness.

The flat key that embodies this quality with particular poignancy is E flat major – at least, that’s how it seems when one encounters it in Beethoven. His late, great String Quartet Op. 127, the ‘Eroica' Symphony and the ‘Emperor’ Piano Concerto are all in this key.

There’s a similar spaciousness, tinged with awe, in Mozart’s E flat major music, particularly the pieces he wrote with Masonic connections, such as the Piano Concerto K482 and the Magic Flute (three is a significant number for Masons, thus the use of a key with three flats).

Surely the most spacious and mighty of all these E flat major pieces is to be found in Wagner. His Ring cycle begins with several minutes of unblemished E flat major harmony.

C sharp major (D flat major)

The great philosopher Heraclitus remarked that ‘when taken to extremes, opposites meet,’ and that’s certainly the case with keys. Pursue the circle of keys to the maximum distance from ‘homely’ C major in either direction, and you find yourself at a point when ‘sharpness’ and ‘flatness’ do actually meet.

A key that has this curious ambiguity is the one that begins on the note C sharp. C sharp major has seven sharps, and is so rare that it’s hard to ascribe much character to it – though there is perhaps a peculiar magical brightness in pieces such as Transports Op. 63 by Charles Alkan, the slow movement of Poulenc’s Two-Piano Sonata and ‘Ondine’ from Ravel’s Gaspard de la Nuit.

The really extraordinary thing is that when composers spell this key as D flat major (rather than C sharp major), a completely different kind of music emerges – spacious and mysteriously serene, as in the slow movement of Beethoven’s ‘Appassionata’ Sonata and Chopin’s D flat major Nocturne.

E flat minor

Most music is written in sensible keys with only a few sharps or flats, partly to avoid the fatigue of complicated key signatures. But this distance and awkwardness seems to go hand-in-hand with expressive oddity.

There’s a parallel with human character. Madmen and geniuses live at a higher pitch of intensity than ‘normal’ people, but they lack the wide middle ground of feeling. So it is with keys. The remote ones come across as slightly pathological, and therefore of limited use.

A good example is E flat minor, sometimes encountered in its alternative ‘spelling’ of D sharp minor. Charpentier described it as ‘horrible, frightful,’ and Christian Schubart said it evoked ‘Feelings of the anxiety of the soul’s deepest distress, of brooding despair, of blackest depression, of the most gloomy condition of the soul.’

Russian composers seem to favour this strange region. It’s the key of (among others) Prokofiev’s Sixth Symphony and Rachmaninov’s famous Elegie Op. 3 No. 1, and it also gives the opening of Part Two of Mahler’s 8th Symphony a strange colour.

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