After misogyny it is arguably the world's oldest hatred and, as the late Conor Cruise O'Brien noted, anti-Semitism is a "light sleeper".
O'Brien contended that it is found barely beneath the surface even in literature from Shakespeare to Wilde; in public discourse even in societies with tiny or non-existent Jewish populations, and is infectious in its pervasive paranoia throughout the entire Arab and Islamic world.
The 'beast' also raises its head at times when it is least expected, as it did in west Belfast with the desecration of Jewish graves in the City Cemetery.
Politicians and religious leaders have united to condemn the vandalism, which some tried to portray as mindless drink and drug-fuelled behaviour - but now appears to have been something more organised, more targeted, more pointed. After all, the vandals used hammers and blocks to break up the headstones while a larger mob looked on encouraging their actions. There is clear evidence here of forward-planning; the graves targeted being exclusively Jewish, some dating back to the 1870s.
One theory knocking around is that the latest flare-up of anti-Semitism in Belfast is somehow related to the controversy over Celtic being fined by Uefa after their fans displayed Palestinian flags at Parkhead during a European Champions League qualifier this month against an Israeli side. Whatever the motivation, or even the rights and wrongs of the Israel-Palestine question, it is undoubtedly the case that the desecration was motivated by anti-Jew hatred.
There is a depressing binary attitude in Northern Ireland in relation to the Israel-Palestine conflict. If unionists happen to be pro-Israeli and fly the Star of David flags on lampposts in loyalist working-class districts, then naturally nationalists must wrap themselves up in the green, red, white and black colours of the Palestinian cause. In this simplistic black and white vision of a conflict infinitely more complex than our own, there is no room for any grey nuances. You cannot, say for example, be a supporter of a free and independent Palestine while at the same time backing Israel's own right to exist free from the exterminationist tendencies of so many in the Arab world.
This dualistic, simplistic and narcissistic attitude to the Israel-Palestine tragedy (narcissism in the form of seeing every conflict around the world refracted through the prism of the one you lived through here during the Troubles) leads to the repeated vandalism of the blue plaque erected many years ago to commemorate where former Israeli President Chaim Herzog was born in the lower Cliftonville area, or the daubing of anti-Semitic graffiti on the wall of a north Belfast synagogue during the last Gaza war. It helps conjure up that "light sleeper" once more.
Currently there are, sadly, about 80 Jews left living in Belfast and Northern Ireland. It is only recently that the community has been building up enough numbers again to have its own rabbi despite the long benign legacy the Jews who settled in this society from the 19th century bequeathed to us all. There is, for instance, the fountain in Victoria Square that recalls the enormous contribution of the Jaffe family to the city of Belfast from the 19th century, when they fled Tsarist anti-Semitic persecution in Russia.
And it isn't just Belfast that owes so much to the Jewish people. Future Lord Mayor of Dublin Robert Briscoe, who welcomed John F Kennedy to the city in 1962, was a former IRA arms buyer for Michael Collins during the War of Independence. Briscoe later compared his hero Eamon De Valera to a biblical prophet from the Old Testament referring to the Long Fellow as having "the moral grandeur of the Prophet Elijah".
On this island, in this city, unionists and nationalists each owe a great deal to the Jewish influence on politics, culture and business. It is no accident that the author of the greatest novel of the 20th century, Ulysees, chose a Jew as his everyman hero. James Joyce's choice of Leopold Bloom as the main narrator of his masterpiece was quite deliberate. Joyce recognised the genius, the humanity, the intellectual curiosity, the cosmopolitanism their enemies so deride, as the best attributes of our very flawed human condition.
So, it's time to stand by Ireland's Jews once more - and that begins with the community around the City Cemetery offering up the names of the bigoted morons behind the desecration of the graves to the police.