From majikthise :

I'm still trying to figure out why Sufjan Stevens' Casimir Pulaski Day hits me like a ton of bricks every time I hear it.
Just watch, you'll see what I mean.

Here are the lyrics.

The song is about a guy whose girlfriend died of bone cancer. Actually, it's not clear whether the dead girl, to whom the song is addressed, was really the singer's girlfriend, or just someone he tentatively felt up and obsessed about thereafter. (As commenters have pointed out below, it's clear that there was a lot of mutual affection between the two of them, it's just not clear whether exactly what kind of relationship they had.)

Casimir Pulaski Day is the first Monday in March, an American regional holiday to honor a hero of the Revolutionary War known as "The Father of American Cavalry." In today's parlance, the revered CP would probably be described as a "foreign fighter," but that's almost certainly irrelevant to Sujan's song.

Anyway, I think I like the song because it's about someone who believes in God trying to reconcile his faith with reality. The singer is confused about why his God is taking his girlfriend away, even though he and his friends are praying for her.

There's a complementary minor theme about the dead girl's father freaking out about her interest in the singer ("when your father found out what we did that night"). It's almost as if her father has, as an article of faith, the notion that his little girl is a pure, asexual being. Really as the narrator seems to makes clear, she's a normal young woman dying of cancer who, who might well know that she doesn't have much time. Yet this fact doesn't make her father any more reasonable.

To me, the last four stanzas of the song are the most interesting:

"In the morning when you finally go
And the nurse runs in with her head hung low
And the cardinal hits the window

In the morning in the winter shade
On the first of March on the holiday
I thought I saw you breathing

Oh the glory that the lord has made
And the complications when I see his face
In the morning in the window

Oh the glory when he took our place
But he took my shoulders and he shook my face
And he takes and he takes and he takes"

The narrator is describing how, on the morning of his girlfriend's death, a cardinal hits the window. In the last two stanzas, the singer is is seeing God in the bird's blood spattered on the window, but he can't accept that this God he sees on the spattered pane is a god of love or mercy.