Binary Form
A two-part form whose second part usually works its way back to the tonic
Related
Binary form has two parts, usually labelled A–B. The first moves from the tonic to the dominant or a related key; the second starts there, works the material and returns to the tonic. Baroque suite dances often use it, each half repeated.
If the first part closes fully in the new key it is sectional binary; if it stops on a half cadence or mid-modulation it is continuous, and the second must bring the key home. If the later part recalls the opening in the tonic, the form is rounded binary; but only the head of A returns.
Judge binary form by how the two halves divide the work, not by counting themes. A complete, independent return of A makes it ternary; a brief recall that turns to the close is still binary.
Sources
- 二部曲式的类型、反复与回归写法，参 The New Grove Dictionary of Music and Musicians, "Binary form"；本文为原创表述
Used for fact-checking only; all prose is original.