Binary form

Introduction

The word binary has to do with the idea of twoness (think of what you may remember about binary arithmetic, or the way in which the human body seems to be binary--two hands, feet, arms, etc.) In a variety of types of music, the idea of binary or two-section formal plans is important: think of the notion of free-strict in such diverse music as the music of India and Japan, the western prelude and fugue, recitative and aria, the French overture, and many other musics. While this notion of free-strict is important in many genres, we shall focus here specifically on binary form as it occurs in numerous instrumental dance forms (and related or derivative music) from the seventeenth to mid-nineteenth centuries. If one temporarily includes ternary form in the discussion (thus considering what are called the small part-forms, namely two-part and three-part), the repertoire includes such diverse pieces as the dances brought into the French ballet and opera by Lully, the stylized older dances and other movements in the Italian instrumental music of Corelli and other composers, dance movements in the later Baroque (as in the keyboard suites of Bach and Handel), the menuets of the Classical period (as well as the trios that often accompanied them, and the nineteenth-century scherzo and trio), and the small character pieces, waltzes, galops, and mazurkas of Schubert, Chopin, Schumann, and others. Many songs were written in these forms, or variants of them, and even larger vocal pieces such as operatic arias often relied on complex, expanded versions of these forms.

Remember the following as you read and think: what's discussed here is stereotypes and the most "typical" things you'd find in binary form examples; there are always exceptions. Also, don't get confused: periods and double periods are binary forms, in a sense, but we do not usually use the term binary for them because a term like parallel period is more informative.

Simple binary form

This is called "simple" because there is not a return of the opening material at the return of tonic. Here are the most common tonal and formal stereotypes:

Part I                 Part II
|:I--------V-------:||:(various)I----------:||
|:i-------III------:||:(various)i----------:||
          (or v)

Important things to remember:

It's "tonally open"--the first section generally ends in a key other than tonic.
The beginning of part II features an emphasis on the dominant and/or tonal instability; often there's an arrival at a half cadence immediately preceding the return to tonic.
The "new key" is usually well-established before the end of part I, and the tonic is usually re-established before the end of part II.
There is very limited thematic differentiation between parts I and II; there is not the strong contrast you'd expect in something like ternary form.
Therefore, calling binary form "A B" is really a misnomer; it's more like something in between "A A'" and "A B".
In 19th-century binary forms, the first section might well end in the mediant or submediant: third-related keys were more prominently used by Schubert, Schumann, Chopin, and others. Schumann and Chopin were also fond of written-out repeats, sometimes with variations upon the repetition.
Binary forms may be symmetrical (both parts are of equal length) or asymmetrical (the two parts of unequal length; usually the second will be longer).
Part I may be a single or double period, a group of phrases, etc. The beginning of part II is less likely to be a period because of the half cadence preceding the return of tonic. At times, of course, both parts I and II may be longer, thus something like: |: A1 A2 :||: B1 B2 :||
Part 1 may sometimes end in tonic, and thus be tonally closed:
```
Part
  I Part II |:I--------------I:||:(various)I---------:|| |:i--------------i:||:(various)i---------:||
  
```
When this is the case, we'll call it either simple two-part form or simple binary (tonic).
Simple binary form is probably less common than rounded binary form (see below).

Rounded binary form

Part I                Part II      Return of Part I
|:I-------V-------:||:(various) ---I----------:||
|:i------III------:||:(various) ---i----------:||

Important things to remember:

Rounded binary is much like simple binary; the principal difference from simple binary is the return of opening material (thus: "rounded") in the tonic key. The reprise (in tonic) is sometimes literal; it may be part or all of the first section. There's really a wide range of literalness and completeness of reprise; it could also be a varied return. If there's a return of the end of part I at the end of the second, this is called balanced binary.
Rounded binary is thus sort of a hybrid: it contains the restatement of material associated with ternary form; it also contains the 2-part frame, tonally open first part, and thematic similarity of the two parts of binary form.
Just like simple binary, rounded may occasionally be tonally closed (first section concludes on tonic); we'll call this rounded two-part form or rounded binary (tonic).
Rounded binary was frequently the form used in the menuets or trios of the Classical era; the typical arrangement of menuet-trio-menuet (or scherzo-trio-scherzo in the 19th century) is one type of compound ternary form, which you will learn about in the future.

Binary form and sonata form:

Sonata forms may be considered an extension of the basic principles of binary form; in a very real sense, sonata form evolved out of the rounded binary:

|:Part I    :||:Part II    Return of Part I:||
|:I   V     :||:(various)  I       I       :||
|:i   III   :||:(various)  i       i       :||

turns into:

Exposition              Development      Recapitulation
|:P    T     S     K:||:(from Expos.)    P    T    S   K   :||
|:I   --     V      :||:(various,        I         I       :||
|:i   --    III     :||:leading to V)    i         i       :||

P = principal theme; T = transition; S = second theme; K = closing theme

The symbols P, T, S, and K are from the book Guidelines for Style Analysis by Jan LaRue.