Yay for Quatrains
That Emily Dickinson sure knew how to whip out a tidy little poem. This one is yet another great example of just how carefully crafted her poetry is. "The Brain—is wider than the Sky—" is divided into three neat, four line stanzas. If you want to sound all smart and stuff, you can call these stanzas quatrains, because of the whole four line thing.
Iambic Spectacular
The meter of the poem is totally consistent, too. For starters, the whole poem is iambic, meaning that it's divided up into... well... iambs. An "iamb" is an unaccented syllable followed by an accented one. Below is an example from the first line. Read it out loud, accenting the syllable in bold, and you'll get the picture.
The Brain—is wider than the Sky— (1)
Gotta love those iambs. The singsong rhythm propels us forward and takes us through the poem. Notice that the line above is divided up into four iambs, earning this meter the name of iambic tetrameter (because tetra- means four, y'all). But wait, does the next line do the same thing?
For—put them side by side— (2)
Nope, not exactly. In this line, we've only got three iambs. The three iamb thing earns this meter the title of iambic trimeter. Yeah, because tri- means three. If you scan through the rest of the poem—which we highly recommend for sheer enjoyment factor—you'll find that the entire thing alternates between iambic tetrameter and iambic trimeter from line to line, keeping this little poem in a neat and tidy package.
ABCB (Find Out What it Means to Me)
The poem also has a well-behaved rhyme scheme that's not throwing any surprises our way. Basically, it's ABCB the whole way through. Let's look at the second stanza as an example.
The Brain is deeper than the sea—
A
For—hold them—Blue to Blue—
B
The one the other will absorb—
C
As Sponges—Buckets—do—
B (5-8)
So, there you go. The second and fourth line of each stanza rhyme, and the first and third line um... don't. Notice how Dickinson slips in some extra rhyming words with "Blue to Blue." Yeah, because she's just that cool. Check out the next stanza where she pulls some other sneaky tricks:
The Brain is just the weight of God—
A
For—Heft them—Pound for Pound—
B
And they will differ—if they do— C
As Syllable from Sound—B (9-12)
Just like in the stanza before, she gets an extra rhyme in there with "Pound for Pound" (3.10), but she also slips in "do" (11), echoing the rhyme scheme from the previous stanza. This lady has all kinds of tricks up her sleeves.
Power Ballad
As it turns out, this form—the alternating lines of iambic tetrameter and trimeter, coupled with an ABCB rhyme scheme—has a name: ballad meter (a.k.a. common meter). It's an old-school form, traditional for songs, hymns, and stories from long ago. Emily Dickinson loved her some ballad meter, and she uses it to great effect here.
P.S. For a fun treat, try singing this to the tune of the "Battle Hymn of the Republic" or "Amazing Grace." You might be surprised by the results.
Note: Dickinson's heavy use of slashes has a big effect on her rhythm as well. Check out "Calling Card" for more on that.