When I thought my collection of short stories, The Actual Adventures of Michael Missing, was ready (it wasn't, but that's another story), I sent it to an agent I had met through a friend, who told me it was very good, but that it just wasn't for her.
She wasn't that into it.
I was living in France at the time, and it was a painful letter to get. I answered her letter with one of my own (this was in the 80s, no email), asking if she could think of anyone who might be "that" into it.
She suggested someone, and I wrote saying, dear Bill/John/Sarah, Wendy says you might be interested in this collection of short stories.
Weeks would pass, I'd get another "not just that into this" letter, and I would reply in the same vein as earlier. Over and over.
One day, I wrote to a woman named Jane at Dell (if I'd known anything about publishing, I would known that this a was hopeless cause) and said I'd be in New York in July, and that I'd just drop by her office and she could tell me what she thought in person.
Which is exactly what I did (and if I'd known anything about publishing, I'd have known that this isn't done, and there's no telling how things might have turned out).
Jane said, predictably, that it was good but not quite right for Dell. I asked if she could recommend someone and she said, "why not try Gordon Lish at Knopf. He likes new writers."
I dropped my manuscript off at Lish's office -- Lish had such a reputation for being a total jerk that I had studiously avoided ever studying with him -- and flew back to Paris.
Boy were my arms tired.
But by the time I got to my mailbox, there was a letter from Gordon saying he loved my work and wanted to publish me.
He later told me he called Jane to thank her for sending me along and she said to him, "oh, I thought it was awful, but I didn't know what to tell him so I just sent him to you."
So even rejections can be full of deceit and yet they can be the best thing that ever happens to you. I still tell myself this every time my current new novel, The What Do You Know Contest, gets rejected, but it still hurts like hell.
Rejection sucks, and you know that when you tell yourself that it was meant to be, and that something good will come of it, you're just jacking yourself off.
But jacking yourself off is okay when the alternative is no sex at all.
And that's all I have to say about rejection except that it's often about you, but it's mostly about the other person and how fucked up they are, and anyone who can't see what a prize you are doesn't deserve you anyway.

