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How Classical Music Works

Form 1: Binary form / the Baroque dance form

If the piece is in a major key, this related key will almost always be the dominant – the key of the fifth degree of the scale; whereas if it is in a minor key, this related key will almost always be the relative major – the key that shares all the scale notes with it but which has the minor mode's third degree as its tonic.

Form 1: Binary form / the Baroque dance form

Binary form, as the name suggests, is a form comprised of two parts, which we'll call the A section and B section. In theory a work in binary form could take many shapes. In practice, as this form is observed in Western Classical musical history from the Baroque era onwards, it is quite a specific construction with a whole series of expectations attached.

The basic form - schematic

The basic form is remarkably simple.

The A section

The key function of the A section is to establish the tonic key, and then modulate to a related key (see note). This section is then repeated.

The B section

The B section modulates from the related key back to the tonic key via a series of modulations. This section is then repeated.

That's it!

Here's a schematic diagram of the form:





These symbols are used in musical notation and as a result in musical schematic diagrams. They signify that the music between them and the corresponding symbol that is their mirror image is to be repeated.





You will be able to read about variation forms in a later article.

Chords are collections of simultaneously-sounding notes. In classical music they are almost always comprised of three or four simultaneous notes of particular patterns. An implied chord might be when one instrument (in this case a cello) either outlines consecutively the pitches of these chordal patterns, or plays figures that would typically be played over chordal movement of a certain kind.

This simple form is utilised through almost all Baroque dance suites (with the exception of the prelude if there is one, and any variation-based dances like the Chaconne, which occur relatively rarely (see note)). It is however much more prevalent even than this, being the skeleton of, for example, keyboard works of the early classical period like the 555 Scarlatti keyboard sonatas.



More detailed description of how the form is built


Let's talk in slightly more detail about how the form works in practice, and use a familiar musical example to follow along.


We're going to use the Courante from Bach's 1st Cello Suite in G major. Let's listen to the whole piece once before we break it down.

A section


The A section presents a musical idea or theme in the tonic (the home key). This might be a short musical phrase or tune, or a little more. This culminates in what is called a cadence, a pair of chords (actual or implied (see note)) which tell the listener definitively where the tonic is.


After that initial presentation, the idea is elaborated by picking up one or two musical ideas in the initial theme, but this time introducing notes foreign to the tonic key in order to effect the modulation to the new key. The introduction of these new notes to effect the modulation usually immediately follows the conclusion of the first musical phrase.


Once the new key is established, there is some additional material in the new key which confirms it as our new 'home'. This culminates in another cadence, but this time establishing the new key rather than the original tonic.


The section is repeated.

B section


The B section typically begins with a partial restatement of the original musical theme but now in the new key. Quickly however, notes foreign to this related key are introduced to effect a modulation.


Modulations occur a few times, allowing the music (all the while using the material outlined in the first half of the piece) to visit several different keys, all of which are closely related to the tonic. This is often perceptible as the music having a certain roaming quality to it, never quite settling in one place.


There will usually be at least one cadence in a second related key in this section – a moment of stability but perhaps (hopefully) we have the sense that this is not our final destination - the music would not be satisfying if it ended here.


Eventually the music modulates back to the tonic.


At this point there is a partial repeat of the original material of the A section. The music concludes with a cadence in the tonic.

The section is repeated.


Enriched schematic

Let's include a little bit more detail into our schematic diagram of binary form on the basis of what we've just listened to:

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Cello Suite no.1 in G - Courante

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1st phrase establishing tonic, culminating in a cadence

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modulation to the new key

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reinforcement of the new key, culminating in a cadence

00:00 / 01:08

The whole section is repeated. Let's listen to how this sounds.

00:00 / 00:08

The B section quickly modulates.

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Modulations eventually lead to a cadence in a related key.

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More modulations lead to the tonic.

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Partial repeat of A-section material; cadence in the tonic.

00:00 / 01:37

The whole section is repeated. Let's listen to how this sounds








Modulations to related keys, fairly unstable but with moments of local stability.


Other than the preludes and the variation-based dances I mentioned already, there is for example the Gavotte en Rondeau from the 3rd Violin Partita, which is in a different form which we will cover later.

Robustness and commonness of the form


This form, not only in its broad outline but in most of its details, is pretty exactly replicated across, for example, every dance movement of every suite and partita that Bach composed. You can hear it in every movement of the cello suites, for example (with the exclusion of the preludes). And you can read the little blow-by-blow given above along while listening and you will find that, with rare exceptions (see note), this little roadmap will follow the music perfectly well. (It can also be applied to the Two-Part Inventions, keyboard partitas, violin partitas, violin sonatas, lute suites... etc. etc.)

For example, here's the two-part invention in E major. See if you can use the roadmap above and roughly follow the form by ear. If you can try focus on the auditory feeling of the music modulating, for example the first modulation after the music's initial statement, even better.


It may also be an interesting exercise to try listening to different movements from the cello suites and identifying the same inflection points in the form.

Perhaps all of this will feel like simply giving a name and a more rigorous formal outline to something you have intuitively felt all along, in whatever terms you might have expressed this before.



Tension in the form


Speaking of intuition, you may perhaps have noticed a tension in referring to this as a binary form. In particular, the fact that the music returns to both its original key and (usually, at least partially) its original material at the end, means that the music contains more than a hint of ternary form:


A – B – A


Indeed, Schoenberg, in his musical analyses, tended to refer to the binary form, (incredibly confusingly!), as simple ternary form.


We will later see that this binary form, or simple ternary form, or what for the avoidance of making a call one way or another I'll henceforth tend to call the Baroque dance form, is the germ for a whole family of forms, from the scherzo to the sonata form and all that latter form's incredibly richly varied manifestations. It is the tension inherent in the form that accounts perhaps for its amazing robustness and for the richness that can be extracted from such a simple and elegant construction.

00:00 / 00:25

Bach's 2-part invention in E major

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