By now, you’ve probably heard about author Naomi Wolf’s fateful radio interview on the BBC. Perhaps you’ve heard the interview itself, though if not, you might want to skip it—especially if you’re a writer in any genre and you’ve ever had to cite a fact. Any fact.

Wolf was publicizing her book on the government’s attitude toward homosexuality in nineteenth-century England, Outrages: Sex, Censorship and the Criminalisation of Love (British spelling). The persecution, she said, included “several dozen” executions for the crime of engaging in homosexual acts.

“I don’t think you’re right about this,” presenter Matthew Scott said. The term “death recorded,” he explained, didn’t refer to an actual death but to a judge’s decision to decline to pronounce a death sentence.

The silence that followed, you might imagine, was the sound of an author seeing her career flash before her eyes. (Her U.S. publisher just last week announced a delay in the Stateside publication, originally scheduled for this month.)

I haven’t been hearing a lot of the kind of Schadenfreude that usually attends an author’s fall from grace, presumably because of the nature of the error. Wolf hadn’t committed a conscious subterfuge, such as plagiarism. She’d made an understandable mistake, one that any author might make.

I nearly made it myself, once.

I had been researching the history of the telescope for my book Seeing and Believing: How the Telescope Opened Our Eyes and Minds to the Heavens. I kept coming across references to Galileo having “invented” the telescope in 1609. But I figured that if I’m going to write a proper history of the telescope, I should include details of Galileo’s process of invention. So I continued my research, looking at more academic sources, and I found that telescopes had been circulating as a kind of novelty item in 1608, the year before Galileo’s supposed act of invention. I dug further, until I came across an explanation for the seeming discrepancy: In Galileo’s time, the word “inventor” referred to a person who refined an existing piece of technology, as Galileo had in numerous ways. The term for the person we today would call the inventor was “first inventor.”

The sources I’d initially consulted—the ones citing Galileo as the “inventor”—had probably been echoing one another in a series of misinterpretations dating back to some researcher seeing the word “invention” or “inventor” in a primary-source document and imposing a modern interpretation on it. I easily might have joined them in perpetuating the error if my book weren’t an actual history of the telescope that demanded further research.

But I learned my lesson: Don’t trust your own assumptions about a historical moment. It is, I think, a lesson that applies beyond historical research: Try to see the world through the eyes of your characters—whether a scientist in the seventeenth century, a judge in the nineteenth century, or a fictional creation of your own imagination. Every character inhabits a unique world, which, even if you’re the one inventing it, might surprise you.