[avn2109]

+1 for Coleridge, especially the first stanza of Kubla Khan [0].

Also, I'm surprised to see nobody here recommending A.E. Houseman. His Reveille is my favorite poem:

... Up, lad, up, 'tis late for lying: Hear the drums of morning play; Hark, the empty highways crying 'Who'll beyond the hills away?' ...

[0] http://www.poetryfoundation.org/poem/173247

[aptwebapps]

I read Dirk Gently's Holistic Detective Agency before ever coming across Coleridge's Kubla Khan and spent quite a bit of time (this was before I was on the Internet) trying to find the rest of the poem. I was quite disappointed once I figured things out but on the plus side I understood what happened in the book afterwards.

[delibes]

A personal favourite of mine, by Coleridge :-

http://www.orgs.miamioh.edu/anthologies/bijou/vissat/Workwit...

Why? Because in the movie Groundhog Day, when Phil Connors has had his moment of enlightenment/peripety, he quotes :

"And winter, slumbering in the open air, Wears on his smiling face a dream of Spring!"

Knowing this poem makes the film better. Knowing how widely popular Coleridge became makes the poem better.

[daveslash]

Houseman's a favorite of mine as well.