Grammar Moses: Pray tell me, what's a petard?

It's fun - and sometimes surprising - to learn the literal meanings of everyday phrases you use.

At least it is for Bill Murray and me.

Bill, of Palatine, is a very funny guy who spent 40 years on the other side of the camera in the world of television and who writes mini-books for family and friends with such titles as "News of the Whirled," "New and Improved," which is his take on advertising for unlikely products, and "Bolognia - An Official Archive," his exploration of the nation of Bolognia, which naturally is a bunch of baloney.

"Susan Estrich's Aug. 25 column on Rudy Giuliani's fall from grace contained the phrase " ... he never dreamed he would be hoisted on his own petard,'" he wrote in an email to me. "My recollection is that a petard was a small bomb mounted on a wooden pole or stick that a warrior placed against an enemy's castle door or gate in the 17th century. Apparently the intent was to light the fuse, run up to the fortification, lay the petard against the target and run away before the explosion. If the fuse burned too quickly, or if he tripped along the way, the engineer could be blown into the air, 'hoisted by' not 'hoisted on' his own petard."

I couldn't recall whether Shakespeare coined the phrase "hoist with his own petard" in "Hamlet" or "Coriolanus," but upon further investigation I found it in Act 3 of "Hamlet":

"For 'tis the sport to have the engineer

Hoist with his own petard; and 't shall go hard

But I will delve one yard below their mines

And blow them at the moon."

Not much of the way we spoke or wrote 420 years ago, when Shakespeare published "Hamlet," is intact today.

It's not surprising that such a catchy phrase, used today to connote something backfiring in a figurative sense, might have been bastardized over the years.

Especially when few people today would know what a "petard" is. It's understandable that the original phrase would be altered by changing "with" to "by." They have roughly the same meaning in this context.

But by changing it to "on," Estrich exhibits a lack of understanding of the original meaning.

"Hoisted on one's petard" doesn't quite work. Rudy wasn't propelled to the moon on a Roman candle. He was knocked off his feet by his own actions.

Nevertheless, the trusty Ngram Viewer tells us that the "hoisted by" version is the most popular version in books today, followed the "on" version. Coming in last is the original "with" version.

Would that more of us consulted the easy-to-Google online etymology dictionary to figure out what we were really talking about rather than trusting what an old yarn spinner told us in our youth.

Soft pedaling

My boss last week downplayed something to a group of department heads as a jape. When I learned about the subterfuge, I wrote back to the group, "You really soft-pedaled that!"

Seconds later I thought to my horror I might have given them a homophone with which they could mercilessly badger me during our next meeting.

I thought perhaps the phrase might be "soft-peddle."

Why?

Consider the phrase "sell yourself short." You're not giving yourself the credit you deserve; you're underselling yourself. It would follow that to soft-peddle something would be to sell it short.

Turns out I was right in the first place. It is "soft-pedal."

I'll bet you didn't know this one, either. The soft pedal is the leftmost foot pedal on a piano that softens the music.

Write carefully!

• Jim Baumann is vice president/executive editor of the Daily Herald. You can buy Jim's book, "Grammar Moses: A humorous guide to grammar and usage," at

grammarmosesthebook.com. Write him at jbaumann@dailyherald.com

and put "Grammar Moses" in the subject line. You also can friend or follow Jim at facebook.com/baumannjim.