Revelation is a spooky and difficult piece of writing, and the source for almost all the apocalyptic imagery that has entered into the popular imagination through books, art, and film.

Apocalypse Pretty Soon author Alex Heard is editor of Wired magazine.

The Beast whose number is 666. The Whore of Babylon. The Seven Seals. The Four Horsemen. The Battle of Armageddon. The Second Coming. The very idea of a millennium -- which refers not to the year 1000 or 2000, but to the thousand-year period of peace that will follow the final conflict between the dueling powers of God and Satan -- comes from Revelation 20, where "thousand years" is referred to six times. In Revelation 20:1-2, after the triumph of good, an angel descends from Heaven holding a chain and the keys to the "key of the bottomless pit."

"And he laid hold on the dragon," the passage says," that old serpent, which is the Devil, and Satan, and bound him a thousand years." According to the revelation, after this period of calm Satan will escape for a "brief season" to fight again, but he's doomed to be defeated and cast into a lake of fire. Later, all of mankind, both the living and the resurrected dead, will be lined up for the Last Judgment, with dire consequences for the unworthy - eternal damnation - and eternal life for the blessed. Finally, the old world will be swept away, replaced by a New Heaven and a New Earth.

Revelation is usually attributed to St. John, author of the fourth Gospel, or (by most secular scholars) to a first-century Christian named John who was exiled to the Isle of Patmos, a Greek island, as punishment for performing Christian missionary work. Its composition is usually dated during the Christian-hostile reign of Domitian (81-96 A.D.) or Nero (54-68 A.D.).

Either way, it's been confusing people ever since. The problem is that once you get past the relatively simple plotline, Revelation is as baffling line by line as "The Wasteland." The action starts in chapter 4, where John announces that angels have shown him blinding visions of "things which must be hereafter." The visions describe the triumph of Christian martyrs over evil; soaked with symbolism, they play out with a heavy emphasis on sevens, apparently a numerical symbol of perfection to ancient writers. There are greetings and warnings to seven Christian churches in Asia Minor, seven seals, seven trumpets, seven bowls, seven plagues, a seven-headed whore of Babylon, and a seven-headed dragon. But there's much more going on in Revelation than number games.

Among the highlights: John sees a vision of a heavenly throne surrounded by twenty-four white-robed elders. The throned figure, God, holds a book with seven seals that are successively broken by Christ, who is represented as a slain lamb.

Each broken seal, blown trumpet, and spilled bowl brings forth visions of terrors to come. These include the Four Horsemen, a glimpse of martyrs murdered for their beliefs, earthquakes, a "black" sun, and falling stars. When the seventh seal is broken, John learns that 144,000 faithful Jews, 12,000 from each of Israel's twelve tribes, together with great multitudes who "came out of the great tribulation," will ultimately appear before God, who promises them salvation.

Therefore the action, a chilling array of prophetic detail is chucked out. It's said, for example, that two "witnesses" will appear during the Tribulation, who will be killed by a beast and, after lying unburied on the streets of Jerusalem for three and a half days, ascend to Heaven. Later, the Whore of Babylon shows up, drunk from the blood of martyred saints, and two beasts arise from the sea. One of them, presumed to be the Antichrist (contrary to popular belief, Revelation doesn't use this word; it's found in the First and Second Epistles of John), is the beast whose "number is 666." This evil being requires everyone who wishes to buy and sell goods to "receive a mark in their right hand, or in their foreheads."

On and on it goes. There are dozens of other details like this, some of them utterly indecipherable. The climax begins in chapter 19, with Christ finally charging down from above to knock heads together, bearing little resemblance to the kindly-if-opinionated hippie presented in the Gospels. He's riding a white horse at the head of a heavenly host. His eyes are flaming, he's wearing blood-stained clothes, and, creepily, he has a sword coming out of his mouth, which is usually taken to symbolize the power of the Word.

"What does it all mean? Religious thinkers have puzzled over that one for centuries."

What does it all mean? Religious thinkers have puzzled over that one for centuries. St. Augustine, the great theologian, basically elected to grab the apocalyptic pigskin, drop back deep, and punt. He believed in a Second Coming, but not in a literal millennial kingdom on Earth, and he said that Revelation should be read allegorically, as a symbol for the ongoing spiritual war in the hearts of men. This take, called "amillennialism," dominates Catholicism and the mainline Protestant sects.

Other choices that avoid making the tough call include "preterism" (the Gospels and Revelation were real prophecy, but they pointed to events that have already happened, especially the destruction of the Second Temple in 70 A.D.) and "idealism." Popular among academics and other weak sisters, the latter says that Revelation was a vivid pep talk from John to fellow Christians, allegorizing the ongoing battle between good and evil, which will culminate in the return of Christ.

In response to these rather bloodless interpretations, many faithful Christians, including millions and millions of fundamentalists, Pentecostals, and evangelicals, have essentially said: Uh, thanks, but we'll stick with the truth. It's all going to happen. These are the rock-ribbed "premillennialists," who are sure that we live in an age prior to the literal establishment of Christ's millennial kingdom.

For premills the big question is when. The Bible doesn't say, and Jesus gives hints but never clearly spells it out. In the Olivet Discourse, after a stretch of moody talk about the coming tribulation, he says that "this generation shall not pass, till all these things be fulfilled," words that have caused plenty of head-scratching. Did Jesus mean the generation of people he was talking to? That seemed to be the case (and the early Christians sure expected Him to come back soon), but when it didn't happen, other explanations arose. One was that Jesus spoke in a veiled language about things that would happen in the distant future. Though He warned against predicting exact dates or obsessing on the fulfillment of prophecy - "of that day and that hour knoweth no man" - predicting and obsessing have been impossible for men to resist.

In fact, the prophecy-decoding game has entranced some of the finest minds in history. Luther was an ardent millennialist, as was Isaac Newton, who spent the better part of his golden years analyzing Daniel and Revelation to figure out the date. At one point he leaned toward 1948.

"Many people have claimed to 'know' when Christ will return - David Koresh thought he was another Christ ... this is nothing new. It's been going on almost continuously since the crucifixion."

In our day, many people have claimed to "know" when Christ will return - David Koresh though he was another Christ, and Marshall Herff Applewhite believed that he and his sidekick Bonnie Lu Nettles were the enigmatic "two" of Revelation - but this is nothing new. It's been going on almost continuously since the crucifixion. In the second century A.D., for example, Montanus, a self-proclaimed prophet from what is now Turkey, founded a heretical sect based on his belief that the thousand-year reign of Christ was soon approaching. In preparation, the "Montanists" emphasized a starkly ascetic religious experience, "much given to visionary experiences" as well as "fasting and prayer and bitter repentance."

The amount of millennial hubbub surrounding the year 1000 has long been debated - some scholars say not too much happened, others insist Europe suffered widespread panic - but it's widely agreed that the post-1000 world saw periodic outbursts of millennial theory, hoodoo, and disruption. One of the most influential promulgators of the genre appears in the twelfth century: Joachim of Fiore, a prolific Italian abbot who expected a literal Second Coming, and who divided human history into three ages, the Age of Law, the Age of Grace, and a future, millennial Age of Spirit. Other manifestations were less bookish. In The Pursuit of the Millennium, a 1957 study of millennialism in the Middle Ages, Norman Cohn catalogued a procession of hysterias and murderous popular rampages, often directed against Jews, who were deemed by some Christians to be in league with the Antichrist.

One of Cohn's larger points, though, was that the deadly variety of millennial delusion did not completely disappear with the Middle Ages or the Reformation. In a controversial theses, he argued that it infected the twentieth century in a defining way, mutating into the killer utopian bacillus that poisoned Hitler and Stalin, who believed they were cleaning the world of evil. "For Cohn," writes Michael Barkun, a contemporary millennial scholar, in his book Disaster and the Millennium, "[millennialism's] reappearance in secularized form has been its most sinister incarnation."

"Here is the final transmutation of millenarian scholarship," Barkun concludes, "from exotic sects on the margins of society (in that pregnant phrase, 'the lunatic fringe') to forces at the very center of great events."

From Apocalypse Pretty Soon: Travels in End-Time America. W.W. Norton 1999.