"They're a rotten crowd," I shouted across the lawn. "You're worth the whole damn bunch put together."

If you're reading "The Great Gastby" on the Clean Reader app, that classic line that Nick Carraway calls to Gatsby might look a little different. With your filter set to Squeaky Clean, "damn" disappears behind a gray box. You can click for the closest sanitized equivalent: "darn."

Does it have the same ring to it?

The Clean Reader app was developed by Jared and Kirsten Maughan. "Read books, not profanity," the app's website proudly insists.

Last year, the Idaho couple struggled to find advanced reading materials for their young daughter after she came home from the library with a book that "had some pretty significant swear words in it."

The Maughans knew there were already devices designed to filter profanity on television, but were surprised to find that no e-book equivalent existed. After months of research and development with the Page Foundry company, Clean Reader was born.

The Clean Reader app in action Courtesy of Clean Reader

Users can purchase e-books through the free app and set their desired filter: Clean, Cleaner or Squeaky Clean. The app doesn't have a strict definition of "profanity," but the filtered words include obscenities and some anatomical terms ("breast," for one).

While Clean Reader screens for hundreds of these flagged words, it's no match for some particularly creative authors. Shakespeare and Chaucer's uniquely lurid lines could sneak right through.

Jared Maughan admits that the filters are a work in progress. The Maughans continue to get feedback from readers about words and phrases they've missed. "I'm sure it will be an ever-growing list," he said.

And while the Maughans' daughter was the original inspiration for the app, Clean Reader is designed for both children and adults. Maughan himself uses it, though sometimes with the filter turned off. That's what makes Clean Reader different from edited print versions of books — readers have the option to access the original text if they want.

"It's important for people to know that we are not selling edited or censored books," Maughan said. The e-books sold through the app are the same versions available through Amazon, iBooks or other platforms. The decision to censor the language is entirely up to the app user.

This reflects a shift in power that comes with digital publishing: The control of the book moves from the author to the reader. Previously, writers had to authorize edited versions of their books. Now, readers can choose to access an edited version on their own.

Some authors feel as though they've lost control of their own material. The debate over the app has sparked plenty of discussion online:

Controversy aside, the app has found an immediate following: Users in nearly every state and more than 80 countries have downloaded Clean Reader.

It sparks more than a few questions about the nature of literature. Many classics — "To Kill a Mockingbird," "The Grapes of Wrath," "The Great Gatsby" and more — have landed on banned book lists because of profanity. Now that an app can obscure the obscenities, is it possible that the people who called for banning these books might read them? If so, will the message of these books come through on "Squeaky Clean"?

Authors go to great lengths to craft each sentence; if you sub out a word or two, what changes?

Everything, some authors argue: The rhythm, the tone, the meaning.

In a defense of swearing in literature, Kathryn Schulz wrote "Writers don't use expletives out of laziness or to shock. We use them because sometimes the four-letter word is the best one."

What do you think?

Correction (March 21, 2015): An earlier version of this article stated that the Clean Reader app filters the word "crap," and replaces it with "stuff." This is not one of the Clean Reader's available substitutions.