Nun of the above. (Andrew Medichini/Associated Press)

If you want people not to read a book, give it to them for Christmas. Give it to them for their birthdays with a note on it saying, “This will be right up your alley, Carol!” Download it onto their Kindles. Assign it to them for homework. Suggest it for their book clubs.

Tell them the book is a classic, and most people won’t touch it with a ten-foot pole. Tell them that the book “is a good primer on economic issues.” Write the murderer’s name on the front cover in permanent marker.

If you want to keep people from reading a book, buy them iPhones. I just got an iPhone and I may never read again. All the books that are lying casually splayed on every surface of my apartment will fust, unused.

Preventing people from reading a book requires no great effort. It is, you might say, the express purpose for which most of our civilization has been set up.

Consider: in 2009, slightly more than 1 million books were published. There is a spot 124,397 on the Amazon Bestseller list. It is enough to cast a pallor over the most cheerful scribbler.

If you want to keep people from reading a book, there is only one thing you must avoid.

Never, ever ban the book.

That trick worked once, for Savonarola and the gang, in the days when banning a book meant that the book was no longer printed and the copies were destroyed.

But this was a while ago, back when there were presses to destroy and books with deckle edges and neat leather bindings to pile up and burn. Back in the days when your professional options were knight, priest, lord or serf, rather than unemployed, unemployed, grad school or unemployed. Back when the Catholic Church could quite literally stop the presses, when spending your days in ill-fitted robes, coloring in manuscripts, was considered a viable career option.

But even then it gave a certain cachet to the copies that survived.

These days it’s almost ridiculous.

Consider what happened when the Vatican said that a sexual ethics book by Sister Margaret A. Farley, a Yale professor emeritus, showed “defective undrzerstanding of the objective nature of natural moral law” and posed “grave harm to the faithful.”

Sign me up! everyone shouted. Now it ranks 16th on Amazon’s sales list.

It is hard to ban things these days. Condemnation backfires. You can announce an auto-da-fe, but there is always the chance that it will turn into a block party instead.

Sure, reverse psychology is a familiar trick. But it remains effective. Righteous indignation carries well.

Every few years the media complex seizes, in a fit of panic, on something that Kids Nowadays are doing that you need to watch out for. The Kids are building stills to turn Purell into hard liquor. The Kids are soaking things in vodka that really ought not to be soaked in vodka.

“I had no idea,” everyone says, and suddenly the kids really are doing it.

As a general rule, never ban something that the audience has not heard of. As a schoolchild (I think that’s the singular of schoolchildren, but it sounds odd), I once went on a field trip to some sort of wooded area.

They welcomed us. They explained the safety rules. And then they said: “Do not kick the squirrels.”

A murmur went through the assembled crowd.

“We know that squirrels are exactly the right size to kick,” the guide pointed out. “Just stick your foot under the arch of that small furry back and give it a boot. They fly a good distance, too. But we don’t stand for that here.”

It had never occurred to any of us that squirrels were precisely the right size to kick, or that they flew a good distance. But since that day, I have been unable to shake the idea. Of course. Kick squirrels. How had my entire life up until that point not been entirely devoted to kicking squirrels?

A ban is the best publicity there is. And as the Vatican is now discovering, a condemnation will do in a pinch.

Don’t eat the apple. Don’t read this book. Don’t click this link. “50 Shades of Grey” is awful.

There is no such a thing as bad publicity. (Well, there is, actually, but when was the last time you got an endorsement from Jon Huntsman?)

A little knowledge is a dangerous thing.

Since a certain incident in a garden, the track record of religious authorities in preventing people from accessing forms of knowledge has not been exactly stellar. Nor is this case any exception.

It's a strange irony that more people will read “Just Love: A Framework For Christian Sexual Ethics“ after the ban than before. The book was first published in 2006. Only now are people lining up to peruse its contents. That its keywords are Nun Sex Book probably does not hurt, but the ban is what turned the tide.

The best way to promote something is to denounce it loudly.

If the Vatican had wanted it to remain in the deep back shelves where it would do no harm, they had only to say nothing.