When we say that this poem is written in blank verse, that means a few things:
Got that? Iambic pentameter means that each line has five sets of unstressed-stressed syllable pairs. And if it's blank verse, it won't rhyme.
Blank verse is a common and famous form in English poetry (Shakespeare used it, so you know it must be good). Let’s see how it works in this poem. We’ll put stressed syllables in bold, and split the feet up using slashes:
To him | who in | the love | of Na|ture holds
Commun|ion with | her vis|ible forms, | she speaks
A var|ious lang|uage; for | his gay|er hours
That’s the basic idea. Can you see how the groups of syllables (feet) go da-DUM, da-DUM, da-DUM? That’s the essential pattern of iambic pentameter. Notice also that the ends of the lines don’t rhyme with each other. That’s true in the rest of the poem, too.
Aside from the meter, there’s one other thing we’d like to mention. It goes by a fancy name: enjambment. That refers to the breaking up of a sentence or a phrase over more than one line of a poem. In other words, a phrase or idea spills over from one line into the next. In this poem, almost all of the lines are enjambed. We’ll show you how that works, using the same opening lines:
To him who in the love of Nature holds
Communion with her visible forms, she speaks
A various language; for his gayer hours
Do you see how, instead of completing each thought at the end of the line, the poem forces you to read the next line to finish it? At the end of the first line you're like "Holds WHAT?!" The easiest way to see this is to follow the punctuation – look for the semicolons and periods that mark the end of a clause or a sentence. For example, you can’t really get the meaning of line one, until you’ve read through to the semicolon on line 3. Even then, the first sentence of the poem doesn’t finish up until line 8.
This technique has a couple of contradictory effects. For one, it creates a kind of "stop and start" rhythm that keeps the reader a little off balance throughout the poem. At the same time, it pulls us through from one line to another, keeping up the momentum, forcing us to move on in order to understand what we’ve just read.