The nice thing about being a writer is that there is always more writing-craft to learn. For instance, I recently attended a writers’ retreat where I learned a new word and concept: “interiority.” A sort of x-ray vision into a character. And a new rule: You can show or tell, but never both. Both explained by instructor and award-winning author Maggie de Vries.

I thought I knew all about show and tell: Telling is “he’s happy.” Showing is “he smiles.” With showing, the reader doesn’t have to take the writer’s word for it; the reader can deduce it for herself. Which makes her feel more empathy and connection with the character, and that’s the whole point of writing fiction. Of course, fiction has to include both showing and telling, but most writers do way too much telling and not enough showing.

And then there’s the greater sin of doing both at once. As in, “He opened the box and smiled, happy with his gift.” If he opened the box and smiled, we know he’s happy with his gift. To both show and tell in the same paragraph is to say to the reader, “Just in case you didn’t get it, I’ll tell you too.” Which makes the reader feel vaguely insulted; you’ve underestimated him, or you think he’s stupid.

Then there’s “interiority,” which means going more deeply into the character, into how and why he’s reacting the way he is. “Showing” is the shallow end of “interiority.” Most types of showing are generic. The character sweats when he’s nervous, laughs when he’s amused or happy, clenches his fists when he’s angry, scratches his head when he’s confused. These are how most human beings react emotionally, so they’re obvious and generic.

Interiority means how a particular character reacts in a particular circumstance. Is he the quick-to-anger type, and therefore smashes something up each time overwhelming emotions erupt? Is he hyper-alert and always wary, due to a childhood of abuse? Does he therefore feel a current of electricity course through him when someone he interprets as threatening looks at him? That’s not generic; that’s individual; that’s interiority, actions and reactions totally unique to that individual. To come up with those, a writer has to really think about her character, has to delve into her past, has to come up with some original, atypical reactions.

My reaction is, “huh?” I’ve been writing books for years without having ever come across the word “interiority?” Okay, eat humble pie and get with it. Embrace and apply.