Stephen Ambrose handled his first plagiarism scandal of the week with the graceful humility you’d expect from America’s Uncle History. Over the weekend, the Weekly Standard’s Fred Barnes nailed Ambrose for heisting several passages of The Wild Blue, his recent best seller about World War II B-24 bomber crews, from historian Thomas Childers. Ambrose had footnoted Childers but still passed off Childers’ elegant prose as his own. Ambrose apologized immediately for the “mistake,” blamed it on faulty attribution, and promised to place the text in quotations in future editions.

Barnes and Childers quickly pardoned Ambrose, and the only chiding Ambrose received was for his haste: He has written eight books in five years. He’s a history factory, using his five kids as researchers and assistants to streamline the production process. “He writes so many books. I don’t know how he can avoid making some mistakes,” says former Sen. George McGovern, whose B-24 exploits are the chief subject of The Wild Blue. (Running a history-book mill can raise other complications besides bad attribution. Click here for the disturbing story of how Ambrose got the idea for The Wild Blue.)

Ambrose ducked plagiarism No. 1, but then Forbes.com’s Mark Lewis started digging. On Monday, Lewis revealed that Ambrose lifted sentences from Jay Monaghan’s Custer biography in his 1975 book Crazy Horse and Custer.Two days later, Lewis exposed Cases 3 and 4—pilferage in 1997’s best seller Citizen Soldiers and 1991’s Nixon: Ruin and Recovery.And today the New York Times’ David Kirkpatrick discovered five more swiped phrases and passages in The Wild Blue.Ambrose’s patriots can’t fall back on the factory defense anymore: Two of the cases occurred when Ambrose was an obscure professor, before he became Stephen Ambrose Industries. Ambrose is more defiant than apologetic. Though he says he’ll correct the books, he insists to the Times that, “I am not out there stealing other people’s writings. If I am writing up a passage and it is a story I went to tell and this story fits and a part of it is from other people’s writing, I just type it up that way and put it in a footnote.”

Ambrose’s assertion that he’s not a thief is ludicrous. One plagiarism is careless. Two is a pattern. Four, five, or more is pathology. You can bet that historians jealous of Ambrose (that is, all historians) are this minute combing the rest of his corpus for more evidence of sticky fingers.

Plagiarism bloodlettings occur with a dreary regularity. Every few months, a reporter or writer is caught copying a dozen paragraphs from a newspaper here or stealing a few choice lines from an obscure magazine there. (Every time it happens, colleagues throw up their hands and say, “You moron—didn’t you know that people read [the Washington Post, the National Journal, Martin Amis …]”)

The list of writers snared over the years is long and depressingly impressive: NPR’s Nina Totenberg, who plagiarized a Washington Post story about Tip O’Neill when she was a young print reporter; the New York Times’ Fox Butterfield, who rooked several paragraphs of a Boston Globe story—a story about plagiarism; Alex Haley, who settled with a writer he ripped off for Roots; hot young novelist Jacob Epstein, who took 53 passages from a Martin Amis novel; the New Republic’s Ruth Shalit, caught snipping sentences hither and thither for five different stories; Martin Luther King Jr., who lifted much of his dissertation; Sen. Joe Biden, forced out of the 1988 presidential campaign for serial plagiarism—he then plagiarized his withdrawal speech—etc., etc.

Plagiarists steal good stuff and they steal garbage. Some of the liveliest writing in Epstein’s novel Wild Oats was embezzled from Amis. Ambrose misappropriated many vivid sentences. Newspaper plagiarists generally pirate boilerplate quotes and analysis that would have been easy for them to gather on their own.

No matter what they steal, they fall back on the same excuses, as Thomas Mallon shows in his wonderful plagiarism book Stolen Words. Before the computer age, they blamed their confusing “notebooks,” where they allegedly mixed up their own notes with passages recorded elsewhere. These days, plagiarists claim they mistake electronic files of notes with their own writing.

Plagiarists steal for reasons both profound and mundane. In a few cases, plagiarism flows from some deep psychological wellspring: Epstein, the son of eminent literary parents, stole so much and from such an obvious source that he was clearly “committing literary suicide,” writes Mallon. Some writers plagiarize because they are rushing a project through and probably don’t think they’ll get caught. Some are just exceptionally careless. (Plagiarists do not transgress for the same reasons that fabulists such as Stephen Glass or Patricia Smith do. Click here for why.)

Plagiarists are almost always bright, Mallon notes, and they often write better than those they rob. Shalit, for example, writes like a sparkler, yet stole routine material to fill out her pieces. Ambrose’s books are gripping. Samuel Taylor Coleridge, one of the English language’s masters, thieved huge parcels from German writers.

As the Columbia Journalism Review chronicled in 1995, plagiarists suffer vastly different punishments for similar offenses. Some are sacked for a single misdemeanor shoplifting. Some keep their jobs after numerous felonies. Some are briefly suspended; others sidelined for months. Some pay huge settlements to the writers they have ripped off; most don’t pay a penny. This variation, says Mallon, indicates our deep confusion about plagiarism. “We don’t have a clear set of sanctions for it. We don’t even have a clear idea what it is,” he says. “Thinking about it is really intellectually unformed, even my thinking, and I wrote a book. It is extremely elusive.”

It’s so difficult to think about plagiarism for several reasons. First, all writers, especially good writers, borrow and imitate. That’s how we learn. We are constantly influenced unconsciously by things we read. And it can be hard to distinguish an homage from an imitation from a borrowing from a bank robbery.

Writers are uncertain about plagiarism because none of us are certain that we are innocent. I frequently imitate the style of writers I admire. I surely have recycled snappy phrases I’ve read. I can’t tell you what they are, but I bet they’re out there. I have a fear—which I suspect is shared by most writers—that somewhere, in something I wrote, I may have even stolen a sentence. I don’t remember doing it. I would never do it intentionally. But could I swear that it never happened? No. This is—to steal a phrase—our anxiety of influence.

Plagiarism is also confusing because we don’t know whom it hurts. Plagiarism doesn’t harm readers. They rarely know that something they read is ripped off. If anything, readers of The Wild Blue benefit from Ambrose’s jacking Childers, because they get to read some of Childers’ glowing sentences. (The Wild Blue does commit a crime against readers, but it’s not plagiarism. The book is slapdash. Ambrose seems to have written it between lunch and dinner one day. The Wild Blue bears almost no resemblance to Undaunted Courage or Band of Brothers or Ambrose’s other marvelous pop histories. The Wild Blue exploits Ambrose’s name for a distinctly un-Ambrosial project.)

In a 1997 New Yorker essay, James Kincaid argued that plagiarism should not bother writers so much. Most journalism is mediocre, unoriginal prose, Kincaid says, so writers shouldn’t mind if it gets recycled. Some literary theorists minimize plagiarism for a related reason. They are skeptical of the ideas of authorship and originality, contending that everything new is cobbled together from older sources.

But these scholars, you will note, publish their articles under their own bylines. And both they and Kincaid ignore what makes the plagiarist so sinister. For writers, the act of putting particular words in a particular order is our hard labor. Even when the result is mediocre and unoriginal, it is our own mediocrity. The words are our proof of life, the evidence we can present at heaven’s gate that we have not frittered away our three score and ten.

The plagiarist is, in a minor way, the cop who frames innocents, the doctor who kills his patients. The plagiarist violates the essential rule of his trade. He steals the lifeblood of a colleague. A few paragraphs have made Stephen Ambrose a vampire.