Ever since it made news, I’ve been surprised that two of our most prominent historians have been charged with plagiarizing the work of others.

One of them is Stephen Ambrose, who wrote best sellers on World War II, Lewis and Clark and the making of the intercontinental railroad. The other is Doris Kearns Goodwin, who had big books on the Kennedys, Lyndon Johnson and Franklin Roosevelt.

Why would they bother? You’d think plagiarism would be more common among non-talents, who couldn’t write creatively on their own. Clearly, Ambrose and Goodwin could. So why?

I have a theory. It perhaps explains why people plagiarize at every level, right down to high school kids who copy for assignments.

It’s not about being lazy.

It’s about wanting glory.

So it’s not simply about stealing the words of others.

It’s the more selfish act of stealing the glory and acclaim of others.

It speaks of character. Which is why it’s disappointing to see prominent achievers like Ambrose and Goodwin do it.

Plagiarists usually put forth the same old excuses. They say it was done by research assistants. They say they had transcribed the work of others into their notes, and later thought it was their own. Or they were rushed. See, they write a book a year, and

Such excuses are seldom plausible. Goodwin, for example, has been accused of borrowing passages from more than 90 pages of another historian’s book. And Ambrose, who first acknowledged a single case of borrowed prose in one book, has since been accused of many cases in many of his books.

They aren’t the first successful writers to plagiarize.

Mike Barnicle used to be a talented columnist with the Boston Globe. He was fired a few years ago for a number of missteps. One of them was printing a column that largely stole writings from comedian George Carlin.

Barnicle tried to dismiss it by saying they were “only jokes.” The implication was that it’s different than plagiarizing Shakespeare.

It would have been easy for Barnicle, or Goodwin, or Ambrose, to simply give credit to other authors. But something kicked in that made them want the glory. So they pretended it was their own writing.

If there are two things people can’t seem to get enough of, it’s money and acclaim.

And just maybe, the appetite for acclaim even among seemingly staid historians is the biggest of all.

I should point out that you don’t have to be a professional writer to plagiarize. Plenty of people can do it, especially students, who are often tempted to cheat on term papers, or even math and science tests. A few weeks ago in Kansas, 28 high school students were caught plagiarizing a botany experiment from the Internet.

The motive is usually no different as the cases that have lately been in the news. It’s not simply about getting a good grade, but the glory that comes of it.

It’s a form of greed we don’t often think about, but all have to watch for. Even, perhaps especially, those who are successful.