It’s still in there, isn’t it? Among all the other little nuggets of advice that you collect as you do your journeyman work and try to figure out what your voice is and if you’ve even got one.
It was advice that I very largely ignored, when I was setting out. What I knew was Breeze Hill, Walton, Liverpool, an unreclaimed slum in a city that in the late 70s seemed (only seemed) to be in terminal decline. I was so green, so parochial, even Birkenhead was a little bit exotic to me. London, when I went there on a day trip from school, was another world. At age 16 I’d never left the country, never been on a plane, could count on two hands the number of times I’d been outside the city of my birth. (once to London, once to York, once to Borth in Wales, three or four times to Bradford to stay with my sister Pauline). I was profoundly ignorant in other ways too. To take just one example, the only non-British food I’d ever met was Vesta chow mein (just add water).
So “writing what I knew” would have been very constricting, and I had no interest in trying it. I wrote science fiction and fantasy, exclusively and obsessively, and although I never thought about the reasons for it, one of them was almost certainly because the Andromeda galaxy and the Horsehead nebula were a long way from Walton. I was making a break for it, in my head at least. Later, like so many people in my generation, I did the same thing physically.
Thirty years on, I’ve written nine novels and five hundred comic scripts, almost all of which have been in the area of speculative fiction – in other words, the broad genre highway that leads from sci-fi through fantasy to horror, with magic realism and supernatural thriller as well-paved satellite roads. And I can honestly say that “write what you know” was one of the most relevant bits of advice I was ever given.
Most fantasy is based on fact, in the same way most fictions of any kind are based on fact. You create a dramatic illusion, and you give your readers good and sufficient reasons to invest in it – to suspend their disbelief. You try to build a world that’s internally consistent, settings that feel plausible, characters who are believable and who speak in authentic-seeming voices. In all of this you draw directly on your own experience.
Here’s a banal example. In the Castor novels, I tended to set the action in places that I know. If I had to set a scene somewhere unfamiliar, I’d usually make an effort to visit it with my notebook and maybe a camera. This isn’t a boast about how thorough my method is – these places were almost all in London (or in the case of Thicker Than Water in Liverpool) so it didn’t exactly take a strenuous effort. And it really wasn’t about any kind of duty to truth. It was about creating texture – in this case, creating vivid and believable backdrops to fantastic and implausible action, so the reader’s immersion in the story isn’t threatened by ludicrous clangers or impossible juxtapositions. Because when you get it demonstrably and visibly and glaringly wrong, the dramatic illusion pops like a bankrupt weasel.
Case in point: when I got the functioning mechanics of an automatic handgun wrong in Dead Men's Boots, for readers who knew about handguns (ie Americans) there was suddenly this sense of crashing unreality. This was not the real world - not because a succubus and an exorcist were fighting a horde of undead gangsters, but because the guns didn't work the way they should.
It’s the same with character. You write from what you know about human nature, and for the most part you try to make sure that all your characters fall within the human range as you understand it. This is not to say that you make them conform to types, unless being human is a type trait. You just kit them out with what you think are possible personalities and possible motivations, based on some kind of composite or some kind of extrapolation from the people you’ve actually met and interacted with. What you know is the foundation for everything else. And if you create characters who just plain don't work, your audience will know it and will feel it. They'll be pushed away from engagement with the story.
And this doesn't apply only to "realistic" fiction, whatever that is. It's just as true if you’re writing about gods, demons, fairies and monsters. The human becomes the yardstick for the super-human or sub-human, even where you strike off at odd angles. I wrote Lucifer for seven years in the DC Vertigo comic of that name, and in many ways he was as far from the human template as you can get. Morphologically asexual, incapable of empathy or mercy, largely lacking in imagination, and of course possessing a level of power that allows him at one point to collapse an entire plane of existence just by stepping into it.
But.
I wrote Lucifer as Everyman. The bits of him that mattered most for the story were the bits that emphatically are part of the basic human kit – especially his driving need to find some definition of himself that didn’t depend on his father’s plan and his father’s influence. (For the purposes of the book, Lucifer was one of the three sons of Yahweh, the other two being Gabriel and Michael). So even when the story strayed into other Creations, underworlds and afterworlds, I was basing pretty much everything on my own experience and my own take on the family dynamic.
What you know appears in your stories as texture. It’s the warp and the woof of the fabric you’re weaving. It informs your ability to depict people, places, voices, events in ways that feel realistic within the context of your narrative. Without that bedrock, you’re building on soap bubbles.