A chance encounter after the murderous lorry attack on the seafront at Nice, which killed 86 people who had been enjoying a Bastille day fireworks display in 2016, remains fixed in the mind.
Amid the throng of emergency services personnel, grieving relatives, survivors, journalists and ordinary locals getting on with a semblance of normal life stood a sad, dignified Muslim figure.
Like the killer, Mohamed Lahouaiej-Bouhlel, this was a Tunisian who had made his home in the south of France. Unlike him, Ridha Louafi instantly gave the impression of being a man of decency and reason.
“I am ashamed as a Tunisian of this revolting, cowardly and intolerable act of barbarity,” said Mr Louafi, introducing himself as president of the Cote d’Azur Tunisian Association. “Tunisians and other Maghrebins are among the victims, too, and they are casualties twice over because of the way people will now regard them, as if they were somehow responsible for the terrible actions of one individual.”
His words will never leave me. And their theme, guilt by association, is an important feature of a new book, Republic of Islamophobia, in which a British academic, Jim Wolfreys, describes the rise of "respectable" anti-Muslim feeling in France.
It seems self-evident that demonising all followers of a religion that sub-human ISIL terrorists purport to honour can only be counter-productive, making all resentful and some rebellious. But if Wolfreys is correct, there are ways in which French officialdom aids and abets this process.
The author cites “unprecedented scrutiny of what Muslims wear, eat and say” and argues that excesses of zeal in upholding France’s cherished secular principles have a tendency to “isolate and stigmatise”.
What France desperately needs is a sense of shared community, along with a bold programme to tackle poverty, unemployment and inequality of opportunity for those, including huge numbers of Muslims with roots in North and sub-Saharan Africa, in the deprived banlieues (suburbs of major cities).
In one sense, it works both ways. French Muslims are entitled to expect respect for their faith and traditions. It is not unreasonable to demand, in return, an acceptance of values that include tolerance of unwelcome customs and views, if peacefully and lawfully expressed.
Wolfreys believes there is a danger of confusing understandable fear of terrorism with fear of Muslims. “There is a persistent assumption that Muslims’ religion defines them above all else, and that this uniform ‘community’ bears a shared responsibility for what anyone claiming affiliation to Islam does.”
It is hard to quarrel with that proposition and Wolfreys correctly agrees that hope can be drawn from one gratifying phenomenon: the success of one French institution, the judicial system, in countering the prejudice of sections of another, local government, when overturning the degrading bans imposed by some Mediterranean mayors on the wearing of burqinis.
If hatred or suspicion of Muslims were confined to the hard-of-thinking extreme right, it might not matter much as long as that strand of political allegiance remained a minority, albeit a sizeable one.
President Emmanuel Macron has promised a keynote speech on Islam and France. He might usefully bear in mind that a strong defence of secularism does not need to leave Europe’s largest Muslim population feeling they are the “enemy within”.
But Wolfreys is right to argue that the “dynamics of Islamophobic scapegoating and authoritarianism” can operate only when there is wider compliance and assent.
Attempts to stipulate what may or may not be worn in public or eaten in school canteens, or impose harsh controls on their places of worship, surely imply that wider assent. They do nothing to enhance France’s self-proclaimed reputation as a land of freedom, equality and fraternity.