Oh, Jerusha, I hardly dare write to you, because I'm not a proper writer, not any more. I don't belong on this blog, or the postgrad course I'm doing, or anywhere. Two years work on the novel, and it's a failure. I'm a failure. A friend has just bagged a two-book deal after an auction. My novel's been rejected everywhere it's gone out to. I can't start something new because all my mental and physical energy - my very breath - is on hold for this one. I know that my writing's good, and I've worked and polished and re-worked it. I've taken the feedback I've had on board, and re-worked again. I just haven't written a book that can sell. Why did no one tell me that, before I started? Why did the workshops tweak and poke and sometimes be sceptical but never say, "You shouldn't be writing this novel?" Or why didn't I? How could I have made such a completely wrong decision about what I can make work as a novel? Every now and again, I find some energy to go back to it and try to make it better. I'm not willing to let go yet. And then another rejection comes in, and I'm back where I was.
Oh, Writer it's so hard, and it hurts so much. Rejection of something which you've invested everything in poisons your sense of your self as a writer in a way that few other things can. It is horrible - which is why just pulling your socks up doesn't work, and nor does telling yourself to try harder. But it doesn't have to become toxic, though I know plenty of writers, published and unpublished, for whom it has.
But this is not Failure: the only person who can decide that you've failed is you, and you can decide that you haven't. This is just a tough bit (and yes, BOY is it worse when some thoroughly unnecessary friend seems to be getting all the things which are eluding you). But saying that worse things happen at sea doesn't mean that you're not entitled to swear, weep, get drunk and think that the world is a deeply unfair place, and the book trade the un-fairest bit of it.
What's failed you is your confidence. You may have written the wrong thing, or you may have having written the right thing in a way which, at the moment, is wrong for the book trade. But neither of those says anything about you as a writer, except that, to quote Grayson Perry, "Creativity is Mistakes" (he has that cast into a beam in his workshop). Nor, indeed, does it say anything about what will happen in the end with this novel, let alone in your writerly future. All that's happening is that agents are saying that this book, in this state, they can't sell.
Don't beat yourself up for apparently having only realised you've written the wrong thing (if you have) once you've written it. You're right that workshops tend to tweak and poke, but if you're writing anything more than the dreariest category fiction you may well not be able to tell that it's the wrong thing until you get to the end. I scrapped 50,000 words of A Secret Alchemy, and wrote a completely new story for that strand, and Daphne Du Maurier binned the first 20,000 words of a funny little novel about a second wife and a house called Manderley. The more authors I know, the more we're willing to admit to each other just how much stuff has ended up in the drawer because we just couldn't get it right. And some of the names in that link are very well-known indeed.
Novels, I frequently think, are impossible. They're impossible to get your head round, to write, to 'get' the whole of, and they're certainly impossible to workshop. The scale is just too big. It's like fresco-ing a chapel; you can't be up a ladder painting the curls on the top left-hand angel, and simultaneously the far side of the narthex assessing the balance of the composition between the two domes. Yes, you can do your best to check out the originating ideas, but the detail of doing it comes to have its own logic and momentum.
But if you're writer - and of course you are - you do get back on that horse in the end. It doesn't have to be a macho, clench-that-manly-jaw fight to subdue or scorn your fears, it can be about waiting till there's no more crying to be done, and finding that suddenly it seems really quite peacefully possible.
One thing in your letter rings an alarm bell. You say, "Every now and again, I find some energy to go back to it and try to make it better. I'm not willing to let go yet. And then another rejection comes in, and I'm back where I was." If you've been reading this blog (of course you belong here; don't be silly!) you'll know that while I don't believe that properly focussed revising can "lose the freshness" of work by an experienced writer, I do think that it can be a huge mistake to keep fiddling at something in response to bits of feedback: sudden doubt of your own; something you hear agents love, or hate; something that works brilliantly in someone else's book. This kind of "revising" - which isn't revising - really does risk making a mess of the novel, as you keep chasing after bits that no longer fit properly like a child chopping its own fringe away to a lopsided kind of nothing much.
And no one I know - who I care about - thinks that you're not a proper writer because you've done a serious postgraduate course and the novel you wrote then has been rejected. The majority of Masters novels are. And if you're not a rider till you've fallen off seven times, then, frankly, if I hear of someone who's never had any rejections after some years in the game then I think that either they're a liar or they're not a writer. I also wish them joy of the first rejection they do get - and it will come - because how on earth are they going to cope with it? Good luck!