essentially beautiful. _Variety_ is never so
conspicuous as when united with some intimation of _unity_. For example,
the perpetual change of clouds is monotonous in its very dissimilarity,
nor is difference ever striking where no connection is implied; but if
through a range of barred clouds crossing half the heavens, all governed
by the same forces, and falling into one general form, there be yet a
marked and evident dissimilarity between each member of the great
mass--one more finely drawn, the next more delicately moulded, the next
more gracefully bent--each broken into differently modelled and
variously numbered groups,--the _variety_ is doubly striking because
contrasted with the perfect _unity_ and _symmetry_ of which it forms a
part.

Now, of that which is thus necessary to the perfection of things, all
types and suggestions must be beautiful in whatever way they may suggest
or manifest it. To the perfection of beauty in lines, colors, forms,
masses, or multitudes, the appearance of unity is absolutely essential.
Let the artist look to it, that our pictures may gain expression; our
music cease to weary us through the unceasing dissimilarity of its
parts, highly adorned arabesques running into each other, graceful, but
without significance, without any perceptible principle of unity in the
jarring '_motifs_;' and our poems have some certain theme, that their
highly wrought details may not confuse and bewilder the spirit always in
search of some central unity. Like the burning sands which, clinging not
together in any sweet union of fellowship, blind and confuse us with
their drifting masses, are all such essays in art; for an idea capable
of quickening an artistic creation must be vitally One, and every great
work, notwithstanding its variety and the manifold complexity of its
parts, must form a Whole.

The _association of ideas_, upon which is based the _unity_ of the
continuous life of the individual, with the pervading sense of personal
identity, has been aptly called the '_cohesion of the moral world_.' It
is not less powerful, less irresistible, than that of the physical
world. The association of ideas is a constituent and necessary phase of
the _unity_ of our mental and moral being, the indispensable condition
of all development, whether of mind or soul. Without the power of
association, the intellect would strive in vain to construct consecutive
trains of thought; it would indeed be condemned to eternal i