In Fiction Writing 101, we learned that each element must move the story forward. I agree with this, but, on it's own, that dogma is too simplistic. What does it mean to move a story forward? You can move "King Kong" forward by saying "... and then the ape climbed the Empire State building, reached the top and was killed by airplanes." If we can step forward with a sentence or two, why waste our time with ten minutes of movie, ten minutes in which only learn a few facts? A story is only a story if we move forward in a satisfying way. A trip to Paris isn't fun if we're blindfolded the whole time we're there.
To understand why "Just the facts, ma'am" doesn't work, imagine moving a dinner forward by saying "Salad, then steak and potatoes, then desert," without actually serving any food. That doesn't count as "moving forward." We haven't earned the right to proceed to the second course until we've tasted the first.
Tasting is sensual, and there's the key. Humans are sensual creatures. If we haven't seen, heard, felt, smelled or tasted a thing, we haven't experienced it. If we haven't experienced it, we can't move forward from it. Narratives aren't simply about moving forward; they are about moving forward from one sensual experience to the next.
When we sensualize our stories, we aren't adding spice to them. Sensation isn't spice; it's the world. It doesn't sit on top of the world. It IS the world. In the world, nothing is general, abstract or featureless. There is no such thing as love. There is only the specific love that Charlie feels for Sarah. And Charlie is not a man. He's a specific man with flaking skin on his shoulders, from a day at the Coney Island beach. And we hear the clack, clack, clack of Sarah's heels on the bathroom floor, which is what makes her an actual woman.
We can infuse our stories with sensuality in many ways, the two main ones being via specific details about what's actually happening and metaphor:
1. He rubbed his palm over the gnarled surface.
2. The ship was bigger than four ocean liners laid end to end.
It's not enough to say "It was a really big ship." That doesn't move the story forward, because "a really big ship" is a cheat. It's like claiming you've actually given your son a birthday present when you've given him socks. Any kid will tell you socks don't count as a present (nor does "money for college"). It's like skipping to sex by saying "foreplay" instead of actually kissing an caressing. We have to earn each forward step by sensualizing the moment we're currently in.
There are a couple of traps to look out for: the first is cliche. "Cold as winter" isn't sensual, because we've heard it too many times. We read it as coldaswinter, and it doesn't spark any sensation in our brains. "Colder than a witches tit" is just as bad. Does anyone actually picture Margaret Hamilton's nipples when they read it? (And if they did, would they get a sensation of coldness?) No. It becomes colderthanawitchestit in their brains. This is why we need to continually search for new, surprising metaphors and details. We can't evoke the hero's strength by mentioning his rippling biceps, but we may be able to do it by mentioning that he lifted a hospital bed as if it was a child's cot.
The other trap is over-sensualizing. Imagine never being able to get to dessert because the chef, unsure that he's really earned the right to move on from the main course, keeps serving you more and more steak. Imagine having to stop and examine each pea in a side of peas and carrots. Enough already! And some aspects of the meal aren't really parts of the meal. They're just scaffolding to make the meal possible. The smudge on the wine glass might be memorable, but it's gratuitous if the point of the experience is the Pino Noir.
So how do we know which details to sensualize and which to just report in the abstract. Is it okay to say "He pulled the letter out of the mailbox," or do we need to describe the mailbox's rusty hinges? That's where a lot of the artistry comes in. It's an aesthetic judgement writers have to learn to make, and most improve at making it over time.
One key is to think about which elements are the actual plot points and which are the glue that holds those points together. Say the key points are that the hero hears the mailman drop letters into the box, reads one of the letters and learns his brother has died. The fact that he had to extract the letters from the mailbox isn't a plot point. It's glue. It may be necessary to include it, so that the reader knows that the fictional world follows the same rules as the real world (in which mailmen stuff letters into mailboxes). Another clue is that the character doesn't need to remember it. When looking back on the moment, years later, he'd probably talk about the letter that changed his life. He wouldn't necessarily recall pulling it from the mailbox.
With these glue-like elements, the first decision is whether we need to include them at all. Can the reader infer the mailbox from the items on either side of it, the mailman and the reading-of-the-letter? If it must be included (for the story to make sense or for rhythmic reasons -- maybe we want to build up suspense by pausing before the hero reads the letter...), can we add a sensual details without slowing down the narrative? Glue shouldn't necessarily be included without sensual details. We just want to make sure that such details don't slow the momentum or make the glue more important and memorable than we want it to be. If we answer all these questions in the negative, then we're free to relate the glue -- the mailbox -- as a naked fact, as just a mailbox.
If it's unimportant but necessary scaffolding, sometimes even the slightest detail is clutter. Is there really a point to "brass doorknob"? Maybe it should just be "doorknob." IF the doorknob needs to be sensualized, it probably needs a detail more stirring than "brass."
That which we sensualize will affect the reader -- it will titillate him, scratch him, stroke him or rub him the wrong way; that which we abstract will link two sensual details together. Link as quickly as possible. We need forks in order to eat, but the meal is about the linguini, not the cutlery.