People who are smarter than me -- help with Wordsworth?

So. William Wordsworth. He said this famous thing about poetry: "Poetry is the spontaneous overflow of powerful feelings: it takes its origin from emotion recollected in tranquility." I'm supposed to write a two-to-three-page essay using one of his longer works (Intimations of Immortality, The Prelude, Tintern Abbey) to support and illustrate this idea.

Here's my problem. Something qualified as a "spontaneous overflow" seems to me to be the exact opposite of something "recollected in tranquility", but I still have to write this freaking thing. Can anyone explain this quote to me in a way that will make sense to my tiny, tiny brain?

I'm so glad he's dead.

ETA: I phrased this post as poorly as Wordsworth phrased his definition of poetry. I cannot understand how to illustrate what he's saying about poetry with examples from poems. I mean... unless we know that he sat down in his home and thought "I say, that walk around Tintern Abbey last month; gosh that brings back memories" and then started writing the poem... ?

EATA: I gotta say I'm smiling at all the shared Wordsworth-hatred. BOO-YAH!

EYATA: WE HAVE A WINNAH!

(I still fuckin' hate Wordsworth, though.)