, and
which, imperfect without them as they without it, will, with them, form
one perfect body. Nor is unity even thus accomplished without a
difference and opposition of direction in the setting on of members.
Therefore, among things which are to have membership with each other,
there must be difference or variety; and though it is possible that many
like things may be made members of one body, yet it is very remarkable
that this stricture appears rather characteristic of the lower creatures
than the higher, as the many legs of the caterpillar, and the arms and
suckers of Radiata seem to prove. As we rise in the order of being the
number of similar members becomes less; their structure appearing based
on the principle of two things united by a third;--a constant type even
in matter of the Triune Existence.

Out of the necessity of _unity_ arises that of _variety_, a necessity
vividly felt, because it lies at the surface of things, and is assisted
by our love of change and the power of contrast. It were a mistake to
suppose that mere variety, without a linking principle of unity, is,
necessarily, either agreeable or beautiful.

'All are needed by each one,
Nothing is fair or good alone.
I thought the sparrow's note from heaven,
Singing at dawn on the alder bough;
I brought him home in his nest at even;
He sings the song, but it pleases not now,
For I could not bring home the river and sky;--
He sang to my ear,--they sang to my eye.
The delicate shells lay on the shore;
The bubbles of the latest wave
Fresh pearls to their enamel gave;
And the bellowing of the savage sea
Greeted their safe escape to me.
I wiped away the weeds and foam,
I fetched my seaborn treasures home;
But the poor, unsightly, noisome things
Had left their beauty on the shore
With the sun, and the sand, and the wild uproar.'

It is not mere unrelated variety which charms us, for a forest of all
manner of trees is poor in its effect, while a mass of one species of
trees is sublime;--the swan, with its purity of unbroken whiteness, is
one of the most beautiful of creatures. It is, indeed, only harmonious
and chordal variety, that variety which is necessary to secure and
extend unity (for the greater the number of objects which by their
differences become members of one another, the more extended and sublime
is their unity), which is