The possibility of deviating from the fundamental standard of
phrase-dimension (four measures) has been repeatedly intimated, and is
treated with some detail in the text preceding Example 17, which should
be reviewed. It is now necessary to examine some of the conditions that
lead to this result.
The causes of irregular phrase-dimension are two-fold; it may result
(1) from simply inserting an additional cadence, or from omitting one. Or
(2) it may be the consequence of some specific manipulation of the
phrase-melody with a view to its extension or expansion, its development
into a broader and more exhaustive exposition of its contents.