And get them straight. Know the difference between stalactites and stalagmites because no one likes tripping over stalactites in a cave – it means they’re traveling bat-like, feet up, and feeling nauseous at being upside down. And if you don’t know the difference between elicit and illicit, you may find yourself punctured by barbs volleyed your way by irritated readers. No one likes reading falsehoods, whether in non-fiction or fiction. People want certain inalienable facts to be correct and well established. Even science fiction should begin here on Earth.

As a kid I figured a word in print was a word in fact. I’ll always remember the first time I knew that to be wrong. I’d been reading a kid’s book, not one that was famous or remarkable in any way except that it occupied time in my boring life. The main character was a homely girl with few talents who was looking for something to make her shine – the same thing every lonely kid wants. A friend washes her long hair and discovers that, wet, her hair is curly. Thing is, wet hair, soaking wet hair, is straight. If curly hair is ever going to hang like iron rods, it’s going to be when the shampoo has just been squeezed out. Curly hair releases its springs as it dries, each tendril winding around its invisible cylinder to make a singular corkscrew among hundreds of corkscrews. I know. I have curly hair. I didn’t trust anything else that happened in that book and it was one of the last kid’s books I ever read. Healthy skepticism isn’t a bad trait to have but how unfortunate to have developed it in an activity – reading – I loved.

A colleague is writing a story that included a common if potentially dangerous medical condition, one of those events you learn to recognize when taking emergency first aid courses. Once trained, the markers are obvious, the course of action to protect the victim is well established, and the possible outcomes are reliably documented. When her story detoured through a completely inaccurate set of medical events, from onset of crisis to the all-clear sign, I wondered if she was trying to hint at the characters taking control by faking the medical incident in order to confuse the other characters. Discussion proved that the writer simply didn’t know her stuff and made up a scenario that fit her plot. Unfortunately the whole scene threw the book out of kilter and made what was supposed to be climactic, silly. The tone of the book went from thrilling to ridiculous.

One of my books relates a devastating local event that happened in our city when I was a teenager. It forms the backdrop of the story. A very dear friend who lived right next to the event, a huge fire, gave me first hand information based on what she saw, literally right out her window. She told me things I couldn’t have discovered any other way. But she had one crucial piece of information wrong: the year. I knew the actual year, and it was critical to my story to be accurate. She’d even loaned me the dozen or so saved newspapers with the fire as front page news, the date of the fire on top of every page. It provided a trove of facts and details I’ve incorporated into the story. I chalked up her error and insistence that she was right about the wrong year to stubborn one-ups-man-ship, or to the occasional quicksand of her golden years and her temporal distance from the event. (No, I didn’t argue with her. She was a dear friend and there was no need to point out her one little mistake. I did make it right in my book.)

In Anthony Doerr’s All the Light We Cannot See, the main male character exhibits a gift for building and repairing (and later for finding hidden) radios. In the hands of rebels, radio transmissions reveal secret Nazi strategy. Thus conveyed, partisans are scuttling the Axis war machine. Fascinated by the ability of radios to condense time, to breach borders and allegiances, Doerr learned everything he could about their operation, how they’re built, how they can be located, and how they transmit across radio waves. A world of beauty and horror, of innocence and moral redemption, is made palpable through the simple but thorough descriptions of mollusks, birds, diamonds, and radios, all of it dependent on in-depth knowledge of the actual items.

Isabelle Allende is famous for lapsing into magical realism in many of her books, a jaunt into what is physiologically impossible yet essential to the story. In The House of the Spirits, based on historical events in twentieth century Latin America, the violence and abuse of a powerful male figure is juxtaposed by the loving spirituality of the women around him, and eventually leads to his reformation. One woman famously plays piano without lifting the piano lid. The connection to a world outside of science and pragmatism lends a radiant quality that makes the accurately depicted historical events ever more exquisite and horrible and ultimately comprehensible.

The difference between knowing what’s real yet choosing to present what isn’t, and not knowing the difference, is what makes one writer’s works celebrated, the next, criticized. Writers must build on a scaffold of fact and history. We may deviate but before we leap off the beams, best we know the tensile strength of the steel and the likelihood that we will be able to fly. I want to hear my readers gasp as they soar over chasms, to touch rock safely on the opposite side. Or believe they have.