Blood libels against Jews have been with us from time immemorial. Last week, one occurred in a Swedish tabloid, Aftonbladet, where it was falsely claimed that Israeli troops were murdering Palestinians and harvesting their organs. Rejecting Israeli calls for official condemnation, Swedish Foreign Minister Carl Bildt retorted that freedom of expression had to be protected and that he lacked time to edit "all strange debate contributions [emphasis added]."

This was disingenuous. No one had demanded the curtailment of freedom of speech. Nor does the principle of freedom of speech preclude Carl Bildt from expressing his own view   if it is his own   that such demonization of Jews is obscene. Nor can an imputation of Israeli ghoulishness be properly described as merely a "strange contribution" to "debate."

Yet, in a way, on this last point, Bildt was inadvertently right. A debate of sorts is indeed taking place on whether or not Jews are monsters who stand apart from the mass of humankind. It has in fact been proceeding for some time. Such a discussion has always been the operative, incipient strategy of anti Semitic campaigns. In order to treat Jews as monsters to be extirpated, one must first persuade other people that they are monsters.

Thus, in the space of a few months, there have been other "strange" contributions to this world-wide "debate":

• A Dutch journalist insists in an interview in Holland’s largest daily, De Telegraaf, that the global swine flu pandemic is part of an international conspiracy of Satan worshipping Jews to reduce the world’s population, as were previous outbreaks of bird flu and other forms of flu.

• The Iranian President Mahmoud Ahmadinejad tells a UN conference on racism that Israel is the cruelest and most racist regime based on a fictitious genocide invented by malign Jews.

• A Canadian aboriginal leader is acquitted of seeking to promote racial hatred after saying in an interview that Jews virtually owned all of Germany before the Nazis came to power and that Jews are a "disease…that’s going to take over."

This is not the language of contempt or viciousness that characterizes other hatreds. It moves on an entirely different plane, that of demonization of mythic proportions.

And so it must. Contrary to what is widely believed, anti Semitism is not simply another variety of racism or bigotry. Rather, it is the time honored strategy of assault on the Judeo Christian legacy, adopted by individuals and groups hoping to supplant it. Such an assault requires the demonization of its progenitor, the Jews.

Unlike every other group hatred, therefore, anti Semitism operates even without the usual stimulants for group hatred  economic envy, ethnic animosity or competition for territory or resources.

That is why anti Semitism appears in countries without Jews; attributes supernatural powers and stupendous crimes to them; has been prominent across time and space in diverse ideologies; and has preoccupied groups with real objectives and grievances unconnected to Jews.

As Maurice Samuel put it nearly seventy years ago, "The reluctance to see anti Semitism under the aspect of the revolt against Christ is part of the strategy of that revolt." In short, anti Semitism is not only a problem of the anti Semite, but of an army of bystanders who share a sneaking sympathy for his program.

Other hatreds are also cruel but, as it were, relevant. However, only anti-Semitism could lead an aboriginal leader, confronting vital issues affecting his native constituency, to fixate on supposedly malign, omnipotent Jewish forces. Conversely, there would be no sympathetic hearing available for someone describing, say, the Poles, or the Burmese, or the Nigerians as deliberate plotters of bird flu.

Yet, at best, anti Semitism is treated as but another hatred   which is to say, inadequately.

When the Dutch journalist made her claims of a Jewish swine flu conspiracy, a Dutch anti-Semitism activist said of her that "she does not seem to be right in her head."