Sir Isaac Newton once wrote that he saw farther than others because he had a perch “on the shoulders of giants.”

If you think, as I used to, that Newton was generously acknowledging the intellectual debt he owed to such predecessors as Galileo and Kepler, you’d be wrong too. So say a couple of Web sites I visited while searching for a quotation to help me make the point that I’ll get around to in a minute.

Such quotations are like frozen orange juice. Someone else goes to the work of taking a complex thought and distilling it down to a catchy phrase. All you have to do is thaw it out and serve it to your readers.

You don’t even have to point out, in the case of Newton’s words, that he apparently meant them not as a tribute to earlier scholars but as an insult to his rivals in a feud over credit for a scientific discovery. This, at least, is what the Web site historians say.

It also turns out, though, that Newton may have borrowed more from the giants than a few principles of physics.

As early as the 12th century, Bernard of Chartres is credited with this: “We are like dwarfs standing upon the shoulders of giants, and so able to see more and see farther than the ancients.”

Coincidence? Or plagiarism?

A few words spanning more than four centuries. Was Newton pulling one over on us? It’s a little late now to investigate, but you have to wonder.

There was no wondering this past week, however, when an alert reader called our attention to an act of bald literary piracy that appeared in a letter to the editor. The message of the letter, the pattern of reasoning, the organizational structure and even extended word-for-word passages had been lifted from a recent column in the New York Times and submitted over the perpetrator’s signature.

I hate when that happens.

The relevance of Newton’s words to this column — his lack of originality notwithstanding — is that the public conversation on this page is evolutionary. It grows. Ideally, the writers whose thoughts appear here are engaged in independent thinking even though it may draw on the opinions that others have expressed — just as it may nurture the opinions of those who write next week’s letters. All who participate in the forum are riding on someone’s shoulders, maybe giants’, maybe not, but there’s often a synthesis at work, at least subtly.

Then along comes someone who, like our recent contributor and maybe even Sir Isaac Newton, violates the standards. Borrows without saying so from someone else who is a little more adept, a little more insightful. Steals, actually.

You’d think a regular letter writer would understand the rules, says Kay Semion, associate editor at the Daytona Beach News-Journal and the current president of the National Conference of Editorial Writers, but in fact the idea of plagiarism just doesn’t cross some people’s minds.

Tim Gleason, dean of journalism at my alma mater, the University or Oregon, has a theory about this. Computers and the Internet have so altered the techniques of text manipulation that the boundary between plagiarism and honest research notes has been hopelessly blurred.

If, indeed, that important distinction is being lost on today’s high-tech generations, no wonder sophisticated national organizations are waging such an aggressive campaign to flood the nation’s newspapers with mass-produced letters that supportive Web site visitors can sign and submit to their local papers with a single click. Why compose your own ideas when you can thaw out someone else’s?

A would-be contributor to the letters page of the Medford Mail Tribune told Editorial Page Editor Gary Nelson in an e-mail exchange: “Even ‘exactly identical letters’ submitted with the ‘help of a form letter’ represent an individual’s opinions that are no less valid than if they had been original text.”

Most readers are appalled at the parade of revelations about unscrupulous journalists such as Jayson Blair, Mike Barnicle and others who were caught lifting material from others without attribution. Given the publicity such incidents have received and the rightful indignation that has been hurled at the news profession in general, I’m not sure I totally buy the innocent ignorance theory to explain plagiarism in letters. Most people seem to recognize that it’s wrong.

But if there’s any lingering uncertainty, let me put it this way: We’re interested in original letters, not bumper stickers. The letters forum on this page welcomes your opinions, your rebuttals, your amplifications.

It’s fine to climb up on the shoulders of giants every so often, but please give the giants credit.