I’m new to music theory and the definition of key I’ve learned seems to contradict established fact. I’ve been told that the tonic of a piece is the key where the melody comes to rest, where it feels resolved. And then from there the notes used determine the mode. But, for example, in Chopin’s Fantaisie Impromptu, isn’t the tonic of the first section G#, not C#? Especially in the main melody, where it clearly resolves (and begins!) on G#:


And, given that the piece uses the notes of the E major/C# minor scale, wouldn’t this make the key of the piece G# Phrygian, not C# minor? If the justification for listing the key as C# minor is that the harmony/bass uses C# minor chords, can it be said that the melody is in G# Phrygian while the harmony is in C# minor? Is this a coherent statement?

EDIT: This is the passage that led me to believe G# was the tonic:

melody 2 melody 1

I understand now that the harmony is more important for establishing the tonic than the melody, but if we just consider the melody in isolation here, can it be said to have a tonic of G#? If not, why? It starts and resolves on a G# and it certainly does not resolve on C# the one time it encounters that note. So what is the justification for considering C# the tonic if it doesn’t act as such? Isn’t this being biased towards traditional tonality over a modal explanation? This is the problem I have here.

  • I strongly believe the tonic of the first section is still C# - the music comes to rest on a C# into a C# minor arpeggio in Bar 3, and the previous Bars 1-2 are on G#s that we later find were unresolved. Music and melodies can strongly emphasize the 5th scale degree instead of the tonic - even Chopin's "Ocean" etude (in C minor) ends with the 5th scale degree in the melody!
    – Dekkadeci
    Commented Dec 16, 2022 at 16:46
  • 1
    Baroque, classical, and romantic music is rarely strictly in one key with no chromatic alterations. In particular, a piece or movement in a major key will very often explore the major key that is a fifth higher, and a piece in a minor key will often explore the major key a third higher and/or the minor or major key a fifth higher. For there to be material leading to a cadence in G# in a piece that is mostly in C# minor would not be unusual at all. It doesn’t change the key of the piece and it’s very rarely helpful to interpret any key areas modally. Commented Dec 16, 2022 at 23:13
  • Your recent edit should be asked as a new question so as not to invalidate the current answers. The analysis of a melody alone is potentially quite different than one that is embedded in a harmony.
    – Aaron
    Commented Dec 17, 2022 at 5:52
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    The entire section you added in an edit has its tonic be E, not G#. Again, music and melodies can strongly emphasize scale degrees other than the tonic. (I am reminded again of one of the second final boss's themes in Kirby Star Allies, "La follia d'amore", and how strongly it emphasizes the 5th scale degree in the melody.)
    – Dekkadeci
    Commented Dec 17, 2022 at 7:27
  • 1
    I’m having trouble with explanations of the tonality which are based on the harmony because to me this melody has an existence separate from the chords in the left hand. If I play the melody on its own without the embellishments, just the first note of each bar, it still sounds the same. The addition of the harmony doesn’t radically change my perception of the melody. So I find it difficult to believe the harmony is establishing the tonic. It seems like the melody has its own tonic, which may not be the same as the harmony’s. Commented Dec 17, 2022 at 12:59

5 Answers 5


Where are you talking about the G# in the melody? In your mm.21-24 example, I see only one place with G# in the melody (treble part) and that is m.24, beat 4. I highlight that in yellow here...

enter image description here

...that G# is harmonized as a G# dominant seventh chord, and it next moves to a C# minor triad, highlighted in blue.

If the justification for listing the key as C# minor is that the harmony/bass uses C# minor chords, can it be said that the melody is in G# Phrygian while the harmony is in C# minor? Is this a coherent statement?

That is not a coherent statement.

Key is determined by tonality, and that is largely a harmonic matter. Even if some music were a single voice melody only, tonal melody often implies harmony in various ways. Harmony is not a justification, it's what makes tonality and key perceptible.

I’ve been told that the tonic of a piece is the key where the melody comes to rest, where it feels resolved.

Kind of. But that description sounds like a lot of non-technical, non-music theory explanations.

You want to make a distinction between a rest in the interior of a piece of music versus the start/end of the music along with the understanding that music often modulates to different keys as the music progresses. When a piece is said to be "in the key of..." the convention is referring to the starting and ending key. All the interior parts of the work may modulate to other keys.

The thing you really want to look for is dominant/tonic harmonic relationships. Cadences are the typical points to look at to find those dominant/tonic relationships. In fact a cadence is the standard musical device used to define when establishment of a key is confirmed.

The opening of this piece has a tonic of C#. It plays a G#, then a C# minor chord, eventually moves through II V I cadential harmony.

It ends with a V I cadential harmony movement, which connects to a coda, so the V I happens quit a bit before the actual end. Also, the very last chord changes in quality from minor to major. That doesn't change the overall mode of the piece. It's more of a chromatic "coloring" at the very end. That device is called a Picardy Third.

Ironically, the section of your excerpt also has a dominant seventh chord in C# minor, but you need to include m. 25 to see it move to I.

It seems pretty clearly in C# minor.

Just a note. I used plain, upper case Roman numerals for the chord analysis to avoid the complications of chord quality and inversions. We don't need the distraction of those details to figure out the key. The II V I progression at mm.7-9, all diatonic, except for the conventional raised leading tone, the B#, and a little auxiliary motion to Fx, only requires identifying the chord roots to understand the cadential harmony establishing the key.

  • Thank you for the very detailed answer. I edited the question to show where I considered G# to be the tonic. Can you have a look and tell me what you think? Thanks. Commented Dec 17, 2022 at 5:43

Michael Curtis is basically right, as usual, but I'd like to make a couple of points.

First, it's absolutely possible to identify a key for most melodies independent of any harmony. The terms "tonic" and "dominant," after all, predate the development of harmony. They are originally melodic concepts.

Most composers harmonize most melodies in the melody's key, but not always. Harmony is much more powerful at establishing a key than is melody, though. As Michael Curtis says, it's largely a harmonic matter, but mot exclusively.

It is in fact possible to take a melody in the Phrygian mode and harmonize it in the relative major key, or the relative minor key for that matter. Bach and his contemporaries did this fairly frequently. But it's nonetheless somewhat unusual, and it doesn't make much sense to analyze a piece that way unless the melody has some independent existence as a Phrygian melody. In most cases, a melody that ends on the third or the fifth of the tonic chord is nothing more than a melody that ends on the third or fifth of the tonic chord.

So, it's not always the case that "the tonic of a piece is the key where the melody comes to rest." For tonal classical music (and much other music) the better way to find the key of a piece is to identify the root of the last chord.

But even there, there will be exceptions. for example, Bach's harmonizations of Phrygian chorale melodies are often best analyzed as being in the relative minor key but ending on the dominant chord, so, for example, the piece is in A minor but the melody ends on E and the harmony ends on E major as the dominant of A minor.

  • Thanks, I’m interested in what you say about harmonising a melody with a different tonic. I edited the question to show another section. Do you think this is an example of this or not? Commented Dec 17, 2022 at 5:45

Based on a later edit and comment on this question:

Considering only the accented melody notes in Bars 13-16, it's actually easier to argue the melody is in F sharp minor than G sharp anything:

  • E sharps are plentiful and are always immediately followed by F sharps, strongly implying that the E sharps are leading tones and therefore F sharp is the tonic
  • The melody can be plausibly harmonized as C♯-F♯m-C♯-F♯m / C♯m-G♯-C♯m-C♯m / C♯-F♯m-C♯-F♯m / C♯- F♯m-A-C♯ (this obviously isn't what Chopin actually used, though)
  • Taken alone, the melody notes used are F♯-G♯-A-C♯-D♯-E-E♯; this collection cannot be G sharp Phrygian because it contains E sharp

Zoom out and consider all melody notes in Bars 13-16 and a G sharp tonic becomes even more implausible:

  • The melody notes used are G♯-A-B-B♯-C♯-D♯-E-E♯-F♯, already implying great chromaticism and a lack of modal flavour due to the presence of 3 notes in a row separated by a semitone each
  • Especially given that minor-key music often uses a sharpened leading tone instead of a flattened subtonic for the 7th scale degree, taking the voice leading of the full melody into consideration, tonics of F sharp, C sharp, and E are more plausible than G sharp, which is only ever preceded by E, A (accented melody notes edition), E, and B (full melody edition) - never F double sharp or even F sharp like we likely expect for a G sharp tonic
  • With 9 G sharps and 12 F sharps in the full melody, F sharp is more common than G sharp in the full melody, further harming the case for G sharp as the tonic
  • The full melody can be plausibly harmonized as C♯-F♯m-C♯-F♯m / F♯m-D♯°-E-E / C♯-F♯m-C♯-F♯m / E♯ half-diminished 7th-B-Esus4-E, actually making the case that E is the tonic instead as the music rests on E major chords the longest and all E major and E major-like chords are immediately preceded by dominant-function chords in E major or just more E major(-like) chords

Overall, the requested melody of Chopin's Fantaisie-Impromptu contains too many notes not in G sharp Phrygian to be in G sharp Phrygian, the melody notes do not undergo voice leading consistent with G sharp Phrygian, and analyzing the harmony of the requested melody alone reveals that it is in E major instead with heavy tonicization of F sharp minor and C sharp.

  • Thanks, your answer is very interesting and well thought out. I assumed the E sharp/F natural was an example of chromaticism so never considered a possible F# tonic. I'm not completely convinced though because of the occurrence of the D# which doesn't appear in F# minor. I wonder if the melody is passing through multiple modes/keys, as you point out it appears to end in E major. Or perhaps it is just ambiguous. I'm very curious now to see whether it could be harmonised in G# Phrygian. Perhaps I'll try to rewrite the left hand if I have some spare time. Commented Dec 18, 2022 at 13:01
  • I don't really consider the non-accented notes part of the melody but rather an ornamentation and part of the harmony. If I were to modify the harmony I would modify these notes as well. Commented Dec 18, 2022 at 13:05
  • @chopinliszt - I'm guilty of also singing just the accented melody notes in Bars 13-16 whenever I sing Fantaisie-Impromptu (this does contrast awkwardly with my need to sing all the right-hand notes in measures beforehand, though). However, D# does indeed appear in F# minor - D# is in the F# melodic minor scale, which means that D# does get used in F# minor music.
    – Dekkadeci
    Commented Dec 18, 2022 at 13:48

the tonic of a piece is the key where the melody comes to rest, where it feels resolved is of course something that is taught to students to give a basic understanding of what a tonic is, but it absolutely fails to achieve its purpose in this case. The reason is that Chopin intends to create motion, and he does so by not remaining on the tonic, but by modulating, exploring different intermediate tonics, until resolving back to the original one. In this piece in particular it makes sense to study the left hand, as that gives us the harmonic framework this is build upon. We can then try to find cadences and characteristic chords (dominant 7, semidiminished 7) to analyse what our tonic center is at which point. This then gives us something like this:

enter image description here

(done till measure 27 where we return to the first motive in C# minor). We thus see that the piece starts in C# minor, then shortly changes to G# minor (which is the part you had in mind), but quickly changes again to E major, until we resolve back to C# minor.

This concept of leaving the tonic and employing intermediate tonics is what gives the piece tension and what makes it interesting. But the main, big, final tonic of the piece everything eventually resolves to is still C# minor.

  • I don't have the score or an instrument in front of me but I think there's something off with your harmonic rhythm at bar 13, I follow along until there then lose it. That, or I'm just really bad at counting 😅
    – Some_Guy
    Commented Dec 19, 2022 at 15:26
  • oh, reading through again paying attention to the harmonic movement, I think it's just that the 4 4 5 1 should be 2 beats each over 2 bars, but you have the B7 and E as whole bars not minims. Should be Ax4 Bx2 E4 (in beats) not Ax4 Bx4 Ex4. Good overall analysis though, just a little error :)
    – Some_Guy
    Commented Dec 19, 2022 at 15:34

I was just looking through the sheet music for a pop song when I saw something that reminded me of this question. The song was in G major but there was a section where for a few bars the G was sharp and the melody alternated between F# and G# and it was clear that the purpose of this sharp on G was to make the melody avoid hitting the tonic and continue the motion of the piece without letting it terminate on the tonic. This made me think of this question and I suddenly realised that this is very likely what’s happening here.

Take a look at similar melodies that start on G#, such as G#-F#-E-F#-E-F#-C#-E or even just G#-F#-E-F#-E-F#-E, which both clearly resolve to E. It seems like going from G# to F# and then one or two semitones lower creates a strong tendency towards E as the tonic. Additionally, when considered with the harmony which as Lazy pointed out progresses A6-B7-E the evidence for an E major tonic in this section seems pretty overwhelming. Also I have since seen quite a few pop songs including the aforementioned one in G major ending on the 3rd degree of the key without sounding unresolved, so it seems plausible for the melody to end on G# while the tonic remains E. So I would say this section is in E major and the purpose of the E sharp is to continue the melody where it would otherwise encounter the tonic and tend to end soon after.

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