Shakespeare's Sonnet 130
My mistress' eyes are nothing like the sun;
Coral is far more red than her lips' red;
If snow be white, why then her breasts are dun;
If hairs be wires, black wires grow on her head.
I have seen roses damask'd, red and white,
But no such roses see I in her cheeks;
And in some perfumes is there more delight
Than in the breath that from my mistress reeks.
I love to hear her speak, yet well I know
That music hath a far more pleasing sound;
I grant I never saw a goddess go;
My mistress, when she walks, treads on the ground:
And yet, by heaven, I think my love as rare
As any she belied with false compare.
I thought I'd do this one this week, because Alan Rickman actually recited this poem for a CD of British actors doing Shakespeare's sonnets. Basically this poem is saying that he's not going to lie to himself and say that the woman he loves is perfect, but that doesn't matter because he loves all her imperfections. With that, it's making fun of all the other love poems of that time that would say how perfect their woman was.
A lot of people would say that this is the exact opposite of Snape's feelings toward Lily, since he would say that Lily is the most perfect thing to walk the Earth, but I wouldn't say that's necessarily true all the time. Snape probably admits to himself that Lily was stubborn, unforgiving, and annoyingly cheerful at times, but he loves her anyway.
Plus, I also think this fits very well with how I feel about Snape. People ask me why I like him, even though he was the true hero of the story. Well, yes, I know he made a lot of mistakes. I know that he only switched sides for Lily and would never have done it otherwise. I know he was cruel to Harry and the other students and it couldn't always be justified. But despite his flaws, I still love him. Everyone has flaws, and Snape just has a lot of them.