Now and then an old friend goes through a column of mine, highlights a few phrases, and compliments me on what he calls my "gifted plagiarism." It seems he's picked out various phrases I've borrowed from my betters - and he's kind enough to mention only some of them.

My friend calls it plagiarism; I call it literary allusion. After all, when Cervantes or Shakespeare has said it better, why say it worse?

When caught red-handed with my hands on somebody else's words, the best defense I can frame is, of course, in somebody else's words. Namely, Tom Lehrer's. Specifically, his ditty in honor of the great mathematician Lobachevsky.

For the full effect, Professor Lehrer's aria needs to be sung off-key after a couple of cold ones to the accompaniment of a tinny piano and a loud, vigorous Hey! at the end of each chorus, complete with a stage Russian accent:

"I am never forget the day I first meet the great Lobachevsky. In one word he told me secret of success in mathematics: Plagiarize!"

And on to the verse: "Plagiarize! / Let no one else's work evade your eyes, / Remember why the good Lord made your eyes, / So don't shade your eyes, / But plagiarize, plagiarize, plagiarize - / Only be sure always to call it, please . . . Research!" Hey!

In these computerized times, that kind of research no longer takes the premeditation it did when one had to laboriously type out a quotation. Now, quick, without thinking, we press a key or two and, bingo, somebody else's wisdom can appear under our name.

If and when the slip is noticed, always call it Š Accidental! ("Gosh, I must have copied that in my research and forgotten it wasn't mine.") See the excuses offered by historians Doris Kearns Goodwin and the late, sainted Stephen Ambrose, both of whom were caught sounding entirely too much like someone else.

Harvard Law School is well represented in these distinguished ranks with Lawrence Tribe and Charles J. Ogletree, professors whose words bore a striking similarity to those written by others. The trend starts early at Harvard: An undergraduate there turned out a novel that contained all-too-familiar passages - and got a $500,000 advance for it.

Now a federal judge, the prolific Richard A. Posner, would simplify matters by exempting lawyers and judges from charges of plagiarism. What, not newspaper columnists?

After all, some language is so irresistible that some of us come to think of it as our own. We can't help ourselves. It's the verbal form of kleptomania, this compulsion to appropriate others' clevernesses.

Joe Biden, the senator from Delaware, was once so impressed by some Brit's eloquent speech that he adopted it as his own.

It's understandable why others' good stories and perfect phrases should tempt us to borrow them. What's not understandable is why people would steal bad prose. It's not the theft that troubles in such cases, but the poor taste of the thief.

The late Molly Ivins is my exemplar in these matters. When she was caught sounding word-for-word like Florence King - accidentally, of course - let it be said for Miss Molly that she had the taste to copy from the very best. Originality is a much overrated virtue compared to good taste in collecting.

To quote a once celebrated Southern author, James Branch Cabell, "very few sane architects commence an edifice by planting and rearing the oaks which are to compose its beams and stanchions. You take over all such supplies ready hewn, and choose by preference time-seasoned timber."

Hear, hear! I wish I'd said that. And someday I just might.

It's not imitation but plagiarism that is the highest form of flattery. But always call it Research!