While editing a book on travel writing (circa 1768-1840), I came across a new term: Claude Glass. Intrigued, I looked it up.

A Claude Glass was basically a slightly convex pocket mirror with a surface tinted slightly dark.  These compact mirrors were used by Picturesque landscape artists as a means of isolating an image, so that it could be rendered independent of anything around it. Thus, fewer distractions, for the artist as well as for the viewer. Black mirrors (as they were also called) have the effect of abstracting the subject reflected in it from its surroundings, reducing and simplifying the color and tonal range of scenes and scenery.

Claude glasses could range in size from pocket-size to much larger, as you can see below.

(This is a drawing in the British Museum by the artist Thomas Gainsborough which shows an artist, possibly a self-portrait,  holding a Claude Glass in one hand and drawing implement in the other, to record what he was seeing in the glass behind him onto the paper on his lap. The Claude glass is named for Claude Lorrain, a 17th-century landscape painter, whose name in the late 18th century became synonymous with the picturesque aesthetic.)

You can even make your own Claude glass by using your side rearview mirror. (Warning, things in the mirror may be larger than they appear!)

So, what does this have to do with writing? Too often, writers (myself included) try to squeeze too much information into a sentence, a paragraph, or any other element of writing. We know so much about our characters, for example, that we want to tell everything about them. We want to tell what they look like, give their background and foretell their futures, or describe in the minutest detail where they are walking and what they are sensing. It’s a case of information overload, sure to prompt readers to toss the book (if they’re anything like me) and run screaming down the hall. Overwriting is sure-death for a story.

That’s where the figurative Claude glass can come in handy, helping you to focus only on what is germane to the moment, and letting all else blend into the edges, into temporary (or permanent) obscurity. My friend Meg Gardiner once accused me of “setting the table” when I started a story: putting everyone neatly in their places, their placards filled with information and aligned at their designated spots. She said I was incapable of just leaping into the action, damn the torpedoes, full speed ahead. She was right. (I have since corrected this habit; I think.)

Essentially, when I write, I must make myself use the Claude glass, identifying what should be in focus, and what should fall by the wayside. When my protagonist is standing in the middle of a mine field, is it absolutely necessary that we know that he is six-foot-four, has blond hair, and plays the cello when not at death’s door? No. His size might be important, but I’d have to determine that as I write. Color of hair? Definitely not. Plays the cello? Only important if the cello figures into his death or rescue. Of course, I must know all of this as the author, but I need to use the Claude glasses to determine what the reader must be told. What matters to the story at this moment?

Clarity of focus. Narrowness of vision. Perception of reality. Thanks, Claude!