The Double-period
A third method consists in expanding the period
into a double-period (precisely as the phrase was lengthened into a
double-phrase, or period), by avoiding a perfect cadence at the end of
the second phrase, and adding another pair of phrases to balance the
first pair. It thus embraces four coherent phrases, with a total
length of sixteen measures (when regular and unextended).
An important feature of the
ouble-period is that the second period
usually resembles the first one very closely, at least in its first
members. That is, the second phrase contrasts with the first; the
third corroborates the first; and the fourth either resembles the
second, or contrasts with all three preceding phrases. This is not
always--though nearly always--the case.
The double-period in music finds its poetic analogy in almost any
stanza of four fairly long lines, that being a design in which we
expect unity of meaning throughout, the progressive evolution of one
continuous thought, uniformity of metric structure (mostly in
alternate lines), the corroboration of rhyme, and, at the same time,
some degree and kind of contrast,--as in the following stanza of
Tennyson's:
Phrase 1. The splendor falls on castle walls,
Phrase 2. And snowy summits old in story;
Phrase 3. The long light shakes across the lakes,
Phrase 4. And the wild cataract leaps in glory.
The analogy is not complete; one is not likely to find, anywhere,
absolute parallelism between music and poetry; but it is near enough to
elucidate the musical purpose and character of the double-period. And
it accounts for the very general choice of this form for the hymn-tune.
The following illustrates the double-period, in its most regular and
convincing form (Beethoven, pianoforte sonata, op. 49, No. 1):--
Each phrase is four measures long, as usual; the first one ends (as in
Ex. 50) with one of those early, transient perfect cadences that do not
break the continuity of the sentence; the second phrase ends with a
semicadence,--therefore the sentence remains unbroken; phrase three is
exactly like the first, and is therefore an Antecedent, as before;
phrase four bears close resemblance to the second one, but differs at
the end, on account of the perfect cadence. The evidences of Unity and
Variety are easily detected. The main points are, that the second pair
of phrases balances the first pair, and that the two periods are
connected (not separate periods). See also Ex. 53, first 16 measures.