On 10 September, Geneva comes to a complete standstill. It’s the Jeûne genevois, and many people who have lived there for years still don’t know where it comes from

Thursday 10 September is an official public holiday in Geneva. Not throughout Switzerland, only in Geneva and Neuchâtel. Shops are closed, schools…

Thursday 10 September is an official public holiday in Geneva. Not throughout Switzerland, only in Geneva and Neuchâtel. Shops are closed, schools are not in session, and offices are closed. It is called the Jeûne genevois, the Geneva Fast, and its roots lie in the Protestant Reformation: for centuries it was a day of collective prayer and reflection in times of crisis, epidemics or conflict. All that remains of this today is the public holiday and a tradition that almost everyone finds paradoxical when viewed from the outside: on the day officially known as ‘fasting’, people eat plum cake.

The tarte aux pruneaux is the speciality of the Jeûne. In Geneva’s bakeries, it has been appearing in shop windows for weeks leading up to that date. The historical explanation is that originally people ate simple, meat-free food, and that plums were readily available and in season. Today, the tart remains popular even though fasting has become more of a concept than an actual practice.

If you live in Geneva, make a note of this: Wednesday 9th in the afternoon is the best time to do your shopping, because on Thursday you won’t find much open. And if you have colleagues from other cantons, be prepared for them not quite to understand the following Monday why you had a Thursday off in mid-September. Outside Geneva and Neuchâtel, that public holiday doesn’t exist.