A Dictionary of Music and Musicians/Imperfect
IMPERFECT (Lat. Imperfectus, Ital. Imperfetto). A term employed, in Music, in relation to Time, to Melody, to Cadence, and to Interval.
I. Time. Mediæval writers (accustomed to look upon the number Three—the Symbol of the Blessed Trinity—as the sign of Perfection) applied the term, Imperfect, to all rhythmic proportions subject to the binary division.
The notes of Measured Music were called Imperfect, when divisible into two equal portions. Thus, the Minim—always equal to two Crotchets only—was essentially Imperfect, in common with all other notes shorter than the Semibreve. The Large was also Imperfect, whenever it was made equal to two Longs; the Long, when equal to two Breves; the Breve, when equal to two Semibreves; and the Semibreve when equal to two Minims.
The Imperfection of the Minim, and Crotchet, was inherent in their nature. That of the longer notes was governed, for the most part, by the species of Mode, Time, or Prolation, in which they were written: for, Mode, Time, and Prolation, were themselves capable of assuming a Perfect, or an Imperfect form. In the Great Mode Imperfect, the Large was equal to two Longs only, and therefore Imperfect; while all shorter notes were Perfect, and, consequently, divisible by three. In the Lesser Mode Imperfect, the Large [App. p.684 "Long"] was, in like manner, equal to no more than two Breves. In Imperfect Time, the Breve was equal to two Semibreves. In the Lesser (or Imperfect) Prolation, the Semibreve was equal to two Minims.
But notes, even when Perfect by virtue of the Mode, Time, or Prolation in which they were written, could be made Imperfect; and that, in several different ways.
A Perfect note was made Imperfect, 'by position,' when another note, or rest, of half its value, was written either before, or after it; thus, the Semibreves, in the following example, though written under the signature of the Greater Prolation, were each equal to two Minims only—
Black square notes, though Perfect by the Modal Sign, became Imperfect, in like manner, when mixed with white ones: thus, in the following example, each white Breve is equal to three Semibreves; and the black one, to two only—
Again, the Perfection, or Imperfection, of any note whatever, could be regulated by means of a Point.
Imperfect notes were made Perfect by the Point of Augmentation—the exact equivalent to the dot in modern Music, and, therefore, needing no example.
Notes, Perfect by the Modal Sign, but rendered Imperfect, by position, could be restored to Perfection by a Point of Division, as in the next example, where the first Semibreve, equal, in the Greater Prolation, to three Minims, would be made Imperfect by the Minim which follows it, were it not for the Point of Division placed between the two notes—
In both these cases, the Point serves to augment the value of the notes: but, it may also be made to produce an exactly contrary effect. For instance, a Point of Division, placed between two shorter notes, following and preceding two longer ones, in Perfect Time, served, antiently, to render both the longer notes Imperfect. In the following example, therefore, the Breves are equal to two Semibreves only—
There are other ways in which the Perfection of certain notes may be changed to Imperfection, and vice versa; and, for these, the Student will do well to consult the pages of Zacconi, Zarlino, and Thomas Morley. [See Mode, Time, Prolation, Proportion, Point, Notation.]II. Writers on Plain Chaunt apply the term, Imperfect, to Melodies which fail to extend throughout the entire compass of the Mode in which they are written. Thus, the melody of the Antiphon, Angelus autem Domini (see Antiphon), is in the Eighth Mode; but, as it only extends from F to D—two notes short of the full range of the Hypomixolydian scale—it is called an Imperfect Melody.
[ W. S. R. ]
III. Imperfect Cadence or Half Close. Cadences occupy the position in music which stops do in literature, and of these the Perfect Cadence or full close answers to a full stop, and the Imperfect Cadence or half close to stops of less value. The former consists invariably of a progression towards and a pause upon the Tonic chord in its first position; the latter of a progression towards and a pause on some other chord than the chord of the Tonic in its first position. Both Cadences are to a certain degree dependant on the position they occupy in the group of bars or rhythms which constitute the period or phrase; for when the succession of chords which theoretically constitutes a cadence occurs in the middle of a continuous passage it has not any actual significance of the kind implied by a cadence, but only when it occurs at the end of a period or phrase of some sort. This point is more important to note in relation to the Imperfect than to the Perfect Cadence; since the latter, being absolutely final, is restricted both as to its penultimate and to its ultimate chord; but the former being final only relatively to an incomplete portion of the music, as a comma is to an incomplete portion of an entire sentence, admits of variety not only in its penultimate but also in its ultimate chord; the chief requisites being that the final chord shall be sufficiently clear in its relation to the Tonic and sufficiently simple in its construction to stand in a position of harmonical prominence, and be listened to without any strong craving in the mind for change or resolution; since the chord which comes last must inevitably have much stress laid upon it.
The simplest form of the Imperfect Cadence is an exact reversal of the Perfect Cadence, viz. the succession of Tonic and Dominant harmony, as (a), in the key of C. The Dominant chord is the one most commonly met with as the last in an Imperfect Cadence, but it is capable of being preceded by a great variety of chords other than that of the Tonic in its first position. It is extremely common to meet with the first inversion of the major or minor chord of the supertonic, and even, though more rarely, the first position of that chord, as (b)—
from 'Crudel perchè' in the second act of Figaro. It is also frequently preceded by the first inversion of the chord of the subdominant, both major and minor; and by its first position more rarely. The chord of the submediant does not often occur, but it has been tried, as by Carissimi, as follows
The chord of the augmented sixth is also not unfrequently found, as
from the Fugue in Beethoven's Sonata in B♭, Opus 106.
The diminished seventh which is derived from the supertonic root is also common in various positions as (c) from the second of the Preludes in F minor in Bach's 'Wohltemperirte Clavier.'
As an example of an Imperfect Cadence which concludes on a chord other than the Dominant the following (d) from the slow movement of Beethoven's Violin Sonata in C minor, op. 30, will serve.
Occasionally the Imperfect Cadence appears to belong to another key, which is used transitionally on principles which are explained near the conclusion of the article Harmony (p. 682 a). The following instance is from Mozart's Quartet in G, No. 1.
in which case the two chords forming the Imperfect Cadence are the only ones not in the key of G in the whole passage up to the first perfect cadence, and cannot be considered as constituting a modulation.
The properties of the Imperfect Cadence were apprehended by the earliest composers of the modern harmonic period, and it is frequently found in works of quite the beginning of the 17th century. An example from Carissimi has been given above. In the instrumental music of the epoch of Haydn and Mozart and their immediate predecessors and successors it played a conspicuous part, as the system of Form in Music which was at that time being developed necessitated in its earliest stages very clear definition of the different sections and periods and phrases of which it was constructed, and this was obtained by the frequent use of simple and obvious forms of Perfect and Imperfect Cadences. The desire for continuity and intensity of detail which is characteristic of later music has inclined to lessen the frequency and prominence of cadences of all kinds in the course of a work, and to cause composers in many cases to make use of more subtle means of defining the lesser divisions of a movement than by the frequent use of recognisable Imperfect Cadences.
In Ellis's translation of Helmholtz the term 'Imperfect Cadence' is applied to that which is commonly called the Plagal Cadence. This use of the term is logical, but unfortunately liable to mislead through its conflicting with customary use. The common application of the term which has been accepted above is also not by any means incapable of a logical defence, but it must be confessed to be inferior both in accuracy of definition and comprehensibility to the expression 'Half-close,' which expresses admirably both the form of the succession of chords and the office it most frequently performs in music.IV. For Imperfect Interval, see Iinterval.
[ C. H. H. P. ]