When Mr Le Pen says there is no such thing as racial equality, French opinion might be expected to take this in its stride. It is, after all, part and parcel of the views generally associated with the extreme right, whether in France or anywhere else. But that, for Mr Le Pen's critics, is precisely the point, and as Mr Le Pen's supporters march through Marseilles today, the importance of his comments will be clearer.
The great and the good in France and much of the country's liberal opinion are in a lather of indignation over the remarks by the FN leader in which he said that "races are inherently unequal". Henri Emmanuelli, the former leader of the Socialist Party, and others are calling for Mr Le Pen to be taken to court and for the National Front - a legally constituted political party in France - to be banned. Even some Gaullist politicians have joined the fray, calling for "the law to take its course".
The affair originated two weeks ago, when Mr Le Pen was pressed by a French journalist covering the National Front's summer school to say whether he believed in racial equality. After several attempts at ducking the question, Mr Le Pen finally gave the journalist what he wanted, his view on "inherent racial differences". As days went by, Mr Le Pen was encouraged to elaborate. His only further explanation was to say that "You had only to watch the Olympic Games on television to see that the races are not equal." Whatever that means.
The affair has made the front page of almost every national and regional newspaper in France. "Should the National Front be banned?" asked the left-of-centre Liberation. "The polemic around Le Pen", said the pro-government Figaro, while Le Monde, whose journalist had asked the original question, offered an elegant fence-sitting editorial.
Law officers decided that Mr Le Pen's remarks did not constitute an offence. They appeared to have concluded that expressing an opinion about racial inequality was not the same as "discriminating on racial grounds" or "inciting racial hatred" - both of which are offences. The question is, therefore, why the affair has stirred such a furore in France.
Seasoned French political observers say it reflects the fact that although Mr Le Pen might have been assumed to hold such views on race, he had never actually said so. Hearing his views expressed so baldly, at a time when French politicians and the media have learnt to approach racial subjects with caution, has come as a shock.
There could, however, be another explanation for the explosion of this latest Le Pen scandal now. Last weekend a 16-year-old boy was stabbed to death in Marseilles. The killing took place in the centre of the city in daylight and the story headed the following evening's television news. The dead boy, Nicolas, is white, and the son of a doctor. A 16-year old boy of Arab origin has been arrested in connection with the killing, which has inevitably raised the already high racial tension in the city.
Every six months or so, said one French commentator yesterday, Mr Le Pen provokes a scandal that serves to draw attention to his party; it is part of his political technique. It is a very effective technique; and it is one against which a liberal society has few defences.