e and elastic phraseology,
composers early began to combine three four-measure phrases into a
_twelve_ measure sentence. It is obvious that with three phrases there
can be more subtle effects of contrast and balance than with two, as
the following chart makes plain:

____________
/ \
A Contrast B Contrast C
\____________/
(4 measures) (4 measures) (4 measures)
balance
\______________________________________/

[Music: BEETHOVEN: 6th Sonata]

In this sentence it is evident that we cannot stop at the 8th measure
and that our first definite conclusion is in measure 12. Let the
student observe the varied melodic outline in the three phrases, and
question himself as to the types of cadence and ending.

MINUETTO OF BEETHOVEN'S FIRST SONATA.[58]

[Footnote 58: Lack of space will prevent hereafter the citation in
actual notes of the examples from Beethoven. His works are readily
accessible, and it may even be assumed that every music-lover owns the
Pianoforte Sonatas.]

In this beautifully constructed twelve-measure sentence we have the
main motive of the entire movement set forth in measures 1 and 2;
then a contrasting secondary motive in measures 3 and 4. The second
four-measure phrase, _i.e._, measures 5, 6, 7 and 8, repeats the
material exactly, but with a modulation into the relative major. In
measures 9 and 10 we find the secondary motive appearing in the alto
voice (which should be brought out in performance), and in measures 11
and 12 a free ending in the relative major. The closing measures, 13
and 14, give an echo-like effect, which will be explained when we come
to extended sentences. Such a sentence is not to be considered as one
of 14 measures, although the literal counting gives that number; for
the first complete cadence occurs in the 12th measure at the end of
the third four-measure phrase; the remaining measures being
supplementary.[59]

[Footnote 59: Another excellent example of a 12 measure sentence with
an extended cadence may be found at the beginning of the first
movement of the Third Beethoven Sonata.]

The last type of simple, normal sentence is that of 16 measures,
divided into 4 phrases of 4 measures each. A clear distinction must be
drawn between two successive sentences of 8 measures and the long
sweep of a genuine 16 measure sentence. In the latter case there is no
complete and satisfactory stop until we reach the cadence in the 16th