"Here they come!" Pierre cranes his neck for a better view - and there it is: the first float in the procession through the streets of NiceA city in France. . He gets ready to catch a flower, one of 100,000 that will be thrown to the spectators. With over a million visitors, there will be lots of competition. But as a carnation arcs through the air, he reaches up and... got it!

Nice, where the tradition goes back to the 13th Century, is one of many cities that celebrate Mardi Gras each year. The name means "Fat Tuesday", and - like Shrove Tuesday or Pancake Day in Britain - it is the last day before the beginning of Lent.

To mark the 40 days Jesus spent in the desert, Christians are traditionally supposed to fast or give something up. Mardi Gras originated as a last chance to indulge themselves before it began. In some places it developed into an enormous party.

In Venice people wear elaborate masks and a woman flies down on a zipwire from the famous San Marco bell tower. In Binche in Belgium, men in costumes march through the town throwing oranges to spectators.

Music often plays an important part. In Rio de Janeiro, more than 200 samba schools are involved. New Orleans has a huge jazz tradition, while in Trinidad and Tobago calypso bands compete for the title of Calypso Monarch.

Every major religion apart from Sikhism encourages fasting on special occasions. For Jewish people these include Yom KippurA festival which comes nine days after the Jewish New Year. The name translates as "Day of Atonement".; Muslims have RamadanThe ninth month of the Islamic year, during which Muslims are required to fast from dawn until dusk..

In earlier centuries, Lenten fasting helped people survive. Without modern ways of preserving food, they had to eke out their winter supplies until fruit and vegetables began to grow again in spring.

But in monastic communities, fasting was not confined to Lent. And according to Jamie Kreiner's new book, The Wandering Mind: What Medieval Monks Tell Us About Distraction, it was not just about trying to experience some of Jesus's suffering.

Many monks struggled to keep their thoughts on God as they were supposed to. The Devil, they believed, was constantly trying to distract them. The result was what theologiansPeople who study religion and religious beliefs. called the sin of "acedia", meaning spiritual sloth.

Fasting was an accepted way of combating this. And some think the fact that it has been practised for 2,000 years suggests that it does focus the mind, to some extent at least.  

For health reasons, though, it could obviously not be taken too far. Some monks, rather than restricting their food, decided to make it not very nice, so there was no temptation to eat too much. The 6th Century saint George of Sinai is said to have eaten capers "so bitter they could kill a camel".

Writing in The Conversation during lockdown, Jonathan Zecher suggested that there is a modern version of acedia: "We get distracted by social media, yet have a pile of books waiting to be read... we're bored, listless, afraid and uncertain."

The philosopher Simone Weil argued that real attention was not about struggling to focus, but about emptying our minds so that insights can come to us.

Yes: Many people in developed countries eat more than they need to. It strains the planet's resources and often results in ill health. Fasting helps focus our thoughts.

No: Eating too little is as bad as eating too much - it is vitally important to stay healthy by eating enough food. Fasting does not always help your thinking: you cannot concentrate if your stomach is rumbling.

Or... The best thing is to have a balanced diet. The Ancient Greek maxim "nothing in excess" applies as much to fasting as it does to eating. You can give up an activity you enjoy instead of food for Lent.