This page is a quick-reference. For examples of these functions in musical contexts, see the resource on Classical theme types.
Presentation function comes at the beginning of a theme or phrase. It involves the establishment of the primary melodic material (usually through the use of one or more statements of a basic idea) and the establishment of the tonality of the theme (usually through tonic prolongation).
Antecedent function comes at the beginning of a theme or phrase. It involves the statement of a basic idea followed by a contrasting idea. An antecedent should close with a weak cadence, usually a HC or IAC.
Continuation function comes in the middle of a phrase or theme. It typically involves the breakdown of the primary melodic material and harmonic acceleration towards the cadence.
Following are important terms/concepts associated with continuation function. Not all need be present for a passage to express continuation function, but some should be.
- Fragmentation – Breaking the melodic unit into smaller chunks (for example, following two-bar basic ideas in the presentation with one-bar melodic ideas). Note: fragmentation references the breakdown of the size of the units. Those units are not necessarily related melodically.
- Liquidation – Gradually replacing the characteristic or unique parts of a melody with conventional or common elements.
- Sequential repetition – Repeating the same melodic or harmonic element two or three times, transposed to different pitch levels. This is often used in conjunction with fragmentation.
- Acceleration of melodic rhythm – Changing from predominately quarter notes and eighth notes in the melody to predominately eighth notes and sixteenth notes, for example.
- Acceleration of harmonic rhythm – Chord changes coming more frequently (changing from one chord per bar to two chords per bar, for example).
Cadential function comes at the end of a theme or phrase. It typically involves a cadential harmonic progression and a conventional, descending melodic pattern.
A classical cadential progression begins with the last chord of tonic prolongation and ends with a cadential arrival. The three typical types of cadential arrival in Classical music are the perfect authentic cadence (PAC), the imperfect authentic cadence (IAC), and the half cadence (HC).
A half-cadential progression will begin with the final T chord, progress (optionally) through S, and arrive on a cadential D chord (always D5: V or V7):
T (S) D5
An authentic-cadential progression will begin with the final T chord, progress (optionally) through S, and end with the cadential D T progression (always D5 T1: V(7) I):
T (S) D5 T1
Consequent function resembles antecedent function in that it involves the presentation of a basic idea followed by a contrasting one. Unlike the antecedent function, however, consequent function brings completion to a thematic unit. Therefore, it ends with a strong cadence, typically a PAC.
Just as there is exactly one progression through T (S) D T for every cadence in classical music, there is exactly one progression through presentation – continuation – cadential functions for every cadence in classical music.
None of these functions are optional; all must be present in a normative formal progression.