Is it only a piece of innocent cloth or the thin end of a threatening wedge?
The traditional Muslim woman's headscarf is causing such controversy in some European countries that prime ministers and supreme courts are being asked to decide when it can be worn.
The hijab, as it is called in Arabic, has offended Europe's teachers, bureaucrats and modern-minded women for over a decade. The September 11 attacks in the United States heightened fears that the veil could be covering a head full of radical thoughts.
Germany's highest court tackles the issue on Wednesday when it rules on whether Stuttgart school authorities were right to bar Afghan-born Fereshta Ludin from a teaching job because her headscarf would violate the state's neutrality in religion.
In France, a state commission is debating whether Paris should forbid Muslim girls from wearing a scarf to class.
Not all Europeans have such troubles. The British, for example, generally shrug at the headscarves in their Muslim neighbourhoods as just another part of a multicultural society.
Not all Muslim women in Europe wear headscarves, either. But the ones who do are increasingly teenagers and young women who have grown up in Europe and want their full rights but also consider modesty in clothing an Islamic duty.
Where it is an issue, the headscarf has challenged notions about integration and religious rights. Deeper down, it uncomfortably recalls struggles over religion that modern secular societies thought they had long put behind them.
"This traumatic history is coming back in the confrontation with Islam," the German weekly Die Zeit observed.
RIGHTS, SECULARISM AND SEXISM
Fereshta Ludin's case is the second the German supreme court has handled in as many months. In August, it ruled that Muslim shop assistants could not be fired for wearing a headscarf, despite managers' complaints that they put off customers.
Ludin, a German citizen fully qualified to teach, argues that her constitutional right to practise her religion includes the right to cover her head at work.
In France, the militant secularism born of the church-state struggles a century ago sees the headscarf as a challenge to the modern state that ignores citizens' religious or ethnic ties.
Lacking a clear law against it, though, teachers feel helpless as the scarf-wearing fashion spreads in the poor suburbs where Europe's largest Muslim minority lives.
Women intellectuals also reject the head covering as a sign of a macho view of women challenging the advances Western society has made. "If we accept this symbol, the equality of the sexes is finished," says philosopher Elisabeth Badinter.
Prime Minister Jean-Pierre Raffarin has said he was ready to pass a law banning all religious effects in schools and public offices if the state commission cannot find a compromise.
The headscarf issue is also linked to popular feelings against immigration, as clearly seen in the Netherlands last year when populist Pym Fortuyn -- who was later assassinated -- whipped up a following by railing against Muslim immigrants.
Even in traditionally tolerant Sweden, Nadja Jebril, an ethnic Palestinian, finally won the right to have her own cooking programme on state television after she was originally turned down for another show because of her headscarf.
Fed up with all the fuss, she told an interviewer last weekend: "I am a human being with a lot of feelings and thoughts, not just a piece of cloth."