Sarah and I have been having an intermittent blogversation about writers, writing, and madness, which got started with my post Dancing in the Shadows of Madness. The next two posts in the series are The Shadows Within, and Voices in the Dark. This installment of the blogversation should be pretty much independent, but I hope a few people decide to read the earlier posts anyway.
I personally - not that I'm at all opinionated - think that the kind of creativity capable of generating novels that feel 'real', like the kind of creativity capable of creating great and intense art, music, theater, or for that matter new insights in science, is actually the same thing as madness, just better controlled. Or perhaps better focused.
To conceptualize something that doesn't actually exist vividly enough that you can bring it into a form of existence and make it temporarily real for other people takes a mind that works very differently from the norm. It took me a while to work this out: like most people I thought I was pretty much normal. Yeah, right. And just what is this 'normal' anyway?
It wasn't until I was well into my teens that I realized 'normal' doesn't seek isolated corners to build imaginary cities out of whatever came to hand and devise tales of how the tiny residents lived. 'Normal' doesn't write obsessively (no, nothing from that time of my life is publishable. I was in full angsty-teen by then, and I had no idea about certain techniques like... er... point of view. Not only did I head-hop in the same paragraph, I did it in the same sentence), nor does it read anything and everything it can get its hands on.
Perhaps more to the point, 'normal' doesn't think about everything, much less question most of it, even the most basic assumptions about how things should be. People who knew me then got to dread the question, "Why?". Sure, it was usually asked in a nasal whine - at least partly the legacy of six months of non-stop tonsillitis when I was four, during which I learned to speak nasally because my throat hurt so damn much - but I still wanted to know why things were how they where.
Why? is probably the most useful question in a writer's repertoire, closely followed by, "What then?". Between those two, you get conflict, which drives plot.
To dig out of that little diversion, it's not mentally healthy to question the fundamentals of your society. People build intricate mental models of how the world works so they don't have to think about the things they need to do - because if you stop to think about the mechanics of, say, driving, you're going to get yourself into all sorts of trouble. Upending those models causes chaos, and makes it more difficult to function in the world that generated them.
When the models in question are things like "how my society works", well... It's not hard to see where breaking that one leads. I should add that you don't have to like something to have a mental model of it. It's just that breaking it means you're back to dealing with things from observation and thought, which isn't easy.
Insanity can be considered as the mental state of broken/non-functional models. Sometimes it's chemical: there's a malfunction in how the intricate biomechanisms running the brain work (see Speaker's Lab Rat's Guide to the Brain for a whole lot of information about that). Sometimes it's situational: some circumstance overloads the models and forces them to break down. Usually people recover from the second one, but the first is something you live with, sometimes - like me - with lots of pharmaceutical assistance.
Not everyone can deal with that level of dissonance. I suspect that those who can are what gets labeled creative - they've learned to channel the dissonance into socially acceptable forms and to pretend normality well enough to more or less 'pass' (some better than others. I've become rather better at passing in the last few years. That or ceasing to care what other people think of me is delightfully liberating and no-one is daring to tell me I'm not socially acceptable).
At any rate, the kind of mind that can simultaneously live in ancient Rome with magic, this world, and eldritch battlefields facing all the demons of Hell, is not the kind of mind that gets the stamp of approval from whoever it is that decides what 'sane' is.
Having been given the option of mental hospital (I refused), I know what it's like to have everything break. I wonder sometimes if there's a better way to handle those who can't focus the weird into something acceptable, so long as they're not going to endanger others (if the voices are telling you that you need to kill someone, you do need to be on the wrong side of locked doors for everyone else's safety - unless you kill them in effigy, the way I do in my writing when someone has irritated me enough). I'm not sure that there's a nice easy dividing line, either. Hell, I know there isn't. Depending on how things are doing, I range from 'can pass' to 'needs suicide watch' (that hasn't happened in a long time thank God), and I'm far from alone in that.
The question that disturbs me, though, when I look at how savagely conformist the trends are at the moment (just ask Sarah about the state of schools in the USA), is whether we're killing the creative types before they can learn to channel their differences. Not much can give me nightmares, but the thought of a world without writers, artists, and the like does.