What strikes the historian surveying anti-Semitism worldwide over more than two millennia is its fundamental irrationality. It seems to make no sense, any more than malaria or meningitis makes sense. In the whole of history, it is hard to point to a single occasion when a wave of anti-Semitism was provoked by a real Jewish threat (as opposed to an imaginary one). In Japan, anti-Semitism was and remains common even though there has never been a Jewish community there of any size.
Asked to explain why they hate Jews, anti-Semites contradict themselves. Jews are always showing off; they are hermetic and secretive. They will not assimilate; they assimilate only too well. They are too religious; they are too materialistic, and a threat to religion. They are uncultured; they have too much culture. They avoid manual work; they work too hard. They are miserly; they are ostentatious spenders. They are inveterate capitalists; they are born Communists. And so on. In all its myriad manifestations, the language of anti-Semitism through the ages is a dictionary of non-sequiturs and antonyms, a thesaurus of illogic and inconsistency.
Jean Paul Sartre wrote an essay on anti-Semitism which briefly showed some promise of touching on truth. But then he totally screwed it up by asserting baldly that only the bourgeous classes were anti-Semitic, not workers, a crock if ever there was one.