The violence by Muslims responding to comments by the pope fit a pattern that has been building and accelerating since 1989. Six times since then Westerners have done or said something that has triggered death threats and violence in the Muslim world. Looking at them in the aggregate offers useful insights.

1989 - Salman Rushdie's novel The Satanic Verses prompted Ayatollah Khomeini to issue a death edict against him and his publishers, on the grounds that the book "is against Islam, the Prophet and the Koran." Subsequent rioting led to more than 20 deaths, mostly in India.

1997 - The US Supreme Court refused to remove a 1930s frieze showing Muhammad as lawgiver that decorates the main court chamber; the Council on American-Islamic Relations made an issue of this, leading to riots and injuries in India.

2002 - American Evangelical leader Jerry Falwell called Muhammad a "terrorist," leading to church burnings and at least 10 deaths in India.

2005 - An incorrect story in Newsweek reporting that American interrogators at Guantanamo Bay "in an attempt to rattle suspects, flushed a Koran down a toilet" was picked up by the famous Pakistani cricketer Imran Khan, and prompted protests around the Muslim world, leading to at least 15 deaths.

February 2006 - The Danish newspaper Jyllands-Posten published 12 cartoons of Muhammad, spurring a Palestinian imam in Copenhagen, Ahmed Abdel Rahman Abu Laban, to excite Muslim opinion against the Danish government. He succeeded so well that hundreds died, mostly in Nigeria.

September 2006 - Pope Benedict XVI quoted a Byzantine emperor's views that what is new in Islam is "evil and inhuman," prompting the firebombing of churches and the murder of several Christians. These six rounds show a near-doubling in frequency: eight years between the first and second rounds, then five, then three, one and none. THE FIRST instance - Khomeini's edict against Salman Rushdie - came as a complete shock, for no one had hitherto imagined that a Muslim dictator could tell a British citizen living in London what he could not write about. Seventeen years later, calls for the execution of the pope (including one at Westminster Cathedral in London) have acquired a too-familiar quality. The outrageous has become routine, almost predictable. As Muslim sensibilities have grown more excited, Western ones have become more phlegmatic. Incidents started in Europe (Rushdie, Danish cartoons, Pope Benedict) have grown much larger than those based in the US (Supreme Court, Jerry Falwell, Koran flushing), reflecting the greater efficacy of Islamist aggression against Europeans than against Americans. ISLAMISTS IGNORE subtleties. Rushdie's magical realism, the positive intent of the Supreme Court frieze, the falsehood of the Koran-flushing story (ever tried putting a book down a toilet?), the benign nature of the Danish cartoons or the subtleties of Benedict's speech - none of these mattered. What rouses Muslim crowds and what does not is somewhat unpredictable. Rushdie's novel was not nearly as offensive to Muslim sensibilities as a host of other writings, medieval, modern and contemporary. Other American evangelists have said worse things about Muhammad than did Falwell (Jerry Vines called the Muslim prophet "a demon-possessed pedophile who had 12 wives") without violence ensuing. Why did Norwegian preacher Runar S gaard's deeming Muhammad "a confused pedophile" remain a local dispute while the Danish cartoons went global? One answer is that Islamists having international reach (Khomeini, CAIR, Imran Khan, Abu Laban) usually play a key role in transforming a general sense of displeasure into an operational fury. If no Islamist agitates, the issue remains relatively quiet. The extent of the violence is even more unpredictable - one could not anticipate the cartoons causing the most fatalities and the pope's quote the fewest. And why so much violence in India? These incidents also spotlight a total lack of reciprocity by Muslims. The Saudi government bans Bibles, crosses and Stars of David, while Muslims routinely publish disgusting cartoons of Jews. NO CONSPIRACY lies behind these six rounds of inflammation and aggression, but examined in retrospect they coalesce and form a single, prolonged campaign of intimidation, with more sure to come. The basic message - "You Westerners no longer have the privilege to say what you will about Islam, the Prophet and the Koran; Islamic law rules you too" - will return again and again until Westerners either submit or Muslims realize their effort has failed. The writer is director of the Middle East Forum and author of Miniatures. www.DanielPipes.org

'Islamic law rules you, too'

About intimidating the West, from Rushdie to Benedict.