whole chapters, and many a rambling essay in good standing would permit
pruning without injury, unless indeed we are made to feel that the
apparently dispensable material really contributes something of fullness
and exuberance, and so is not superfluous, after all. The unity in
some forms of art is tighter than in others; in a play closer than in
a novel; in a sonnet more compact than in an epic. In extreme examples,
like _The Thousand and One Nights,_ the _Decameron,_ the _Canterbury
Tales,_ the unity is almost wholly nominal, and the work is really a
collection, not a whole. With all admissions, it remains true, however,
that offenses against the principle of unity in variety diminish the
aesthetic value of a work. These offenses are of two kinds--the
inclusion of the genuinely irrelevant, and multiple unity, like double
composition in a picture, or ambiguity of style in a building. There may
be two or more parallel lines of action in a play or a novel, two or
more themes in music, but they must be interwoven and interdependent.
Otherwise there occurs the phenomenon aptly called by Lipps "aesthetic
rivalry"--each part claims to be the whole and to exclude its neighbor;
yet being unable to do this, suffers injury through divided attention.

Unity in variety may exist in any one or more of three modes--the
harmony or union of cooperating elements; the balance of contrasting
or conflicting elements; the development or evolution of a process
towards an end or climax. The first two are predominantly static or
spatial; the last, dynamic and temporal. I know of no better way of
indicating the characteristic quality of each than by citing examples.

Aesthetic harmony exists whenever some identical quality or form or
purpose is embodied in various elements of a whole--sameness in
difference. The repetition of the same space-form in architecture,
like the round arch and window in the Roman style; the recurrence of