A very old story attributes the burning of the great library at Alexandria, Egypt, to a zealous Muslim ruler, the Caliph Omar, who set to work destroying the ancient world’s greatest collection of books by saying of them, “They will either contradict the Quran, in which case they are heresy, or they will agree with it, so they are superfluous.”

Whether Omar really did and said so is anyone’s guess. Probably not—the anecdote appears only 300 years after the event, in the pages of a book by a vigorously anti-Muslim Christian cleric. But no matter; anecdotally, at least, Omar is the godfather of a line of energetic censors, book-burners and busybodies whose logical culmination is in Ray Bradbury’s now-classic novel Fahrenheit 451.

The novel appeared in 1953, a year that saw a modest quieting of the hysterical anticommunism of the McCarthy period, but, even so, a rise in efforts by school districts to keep bad ideas away from tender schoolchildren—bad ideas whose exponents included Mark Twain, John Steinbeck, Edna St. Vincent Millay, Herman Melville and even William Shakespeare.

Set in the near future—the near future of 1953, that is, meaning somewhere right about now—Fahrenheit 451describes a country caught in the grip of both an external war with another power, presumably the Soviet Union, and a civil war between city dwellers and ragtag anarchists of the woods and byways. The former live in a carefully controlled world of mood-altering pills and big-screen televisions, free of challenging ideas, since challenging ideas make people unhappy. The children of the cities are murderous, life is dangerous, art is abstract and history has been rewritten to provide evidence that the job of firemen—there are no women firefighters in the imagination of 1953—has always involved setting fire to books, rather than putting out fires.

All goes according to the firemen’s plan until, one day, a 30-year-old fireman named Guy Montag begins to ponder his situation, having been asked by a precocious and potentially dangerous teenage girl whether he’s happy. The answer is that he’s not. In fact, he’s miserable, and he compounds his misery by getting his hands on some forbidden books. That’s just as his commander warned would happen: “They’re about nonexistent people, figments of imagination, if they’re fiction. And if they’re nonfiction, it’s worse, one professor calling another an idiot, one philosopher screaming down another’s gullet...You come away lost.”

It is the job of the censors, of course, to keep sheep within the fold and safe from being lost, to keep them happy and entertained. Yet out in the woods, books are memorized and then destroyed—not a bad idea, considering that the firemen are hyperactively vigilant and that the world is subject to being incinerated at any minute.

There are plenty of contradictory books in the world, and plenty of superfluous ones, too. Fahrenheit 451, a book that has not lost any of its power and reads as if written yesterday rather than more than half a century ago, encourages us to be vigilant—to be sure that harm does not come to any of them.