238 FORMS OF HEBREW POETRY
ism, rhythms fall into the two broad classes of
balancing and echoing rhythms. Further metrical
analysis is in detail frequently most uncertain:
but while recognising this uncertainty, it is
important, in order to avoid confusion, to adopt
a method of measurement that is capable of
giving us a clear and sufficient nomenclature.
This is to be found in defining lines or distichs
by the number of the stressed syllables in them.
The exact number of unstressed syllables that
may accompany a stressed syllable may be un-
certain, but is certainly not unlimited.
A single rhythm need not be maintained
throughout a poem, though there were probably
limits to the degree of mixture that was tolerated.
But in particular the elegy, though it commonly
consisted of 3 : 2 distichs, was not limited to
these : it certainly admitted along with these
in the same poem 2 : 2. Mere change from a
longer to a shorter distich of the same class, or
even occasionally from a balancing to an echoing
rhythm, is no conclusive evidence, and in many
poems (for poems differ in the degree to which
they are regular) is scarcely even a ground for
suspecting corruption of text or change of source.
On the other hand, a change in the dominant
rhythm should raise a question whether or not
a new poem has begun.
Finally the question remains whether, though
parallelism in Hebrew seems commonly to have