The "regularity" of the former rhythm imparts a certain stability and squareness to the entire piece, while triple rhythm is more graceful and circular in effect.
(2) The same dynamic distinction applies also to whole _measures_, and (3) to _accents_.

The first of two successive measures, or of two or more accents, is always a trifle heavier than the other.
(4) The _melodic contents_ of the first measure may be exactly reproduced in the succeeding measure; but if this is the case, they are very unlikely to appear still again in the next (third) measure, for that would exaggerate the condition of Unity and create the effect of monotony.
[Illustration: Example 1.

Fragment of Folk-song.] The measure marked _b_ is exactly like _a_.

But _c_ is all the more contrasting, on account of this similarity.
Or, the melodic contents of a measure may be thus reproduced, as far as the rhythm and direction of the tones are concerned, but--for variety--they may be shifted to a higher or lower place upon the staff, or may be otherwise modified.
[Illustration: Example 2.

Fragment of Beethoven.] Compare the groups marked _a_ and _b_, and observe how the principles of unity and variety are both active in these four measures, and how their effect is heightened by the formation of _c_.
(5) The figures of the accompaniment, though reproduced in uniform rhythmic values and melodic direction, undergo constant modifications in pitch and in shape, similar, to those shown in Ex.2.