The Art of No
Ah, the rejection letters. We writers dread them while expecting them, sometimes wish they'd come sooner (why have I been waiting a year, but maybe it's a good sign? Or maybe it's just lost) or wish they'd come later (you rejected me in ONE lousy day, you thought it was that bad?).
Here's a very good essay that speaks very eloquently on the topic, No, by Brian Doyle, featured in the Spring 2008 issue of Kenyon Review. (A particular highlight is Stefan Merkel's rejection letter of a rejection letter, which is brilliant, although the whole article is a very nice rumination on the subject of editing, accepting, and rejecting.) Check it out and keep your chin up.