Never has the sky been so blue, so deep, so fierce with heat. On the side of the road, the burning wind makes her hair swirl. Her delicate gaze is hidden behind her sunglasses. She’s waiting, standing next to her glinting car. Her husband is sitting inside. Patient. She waves, from afar. She smiles coyly, putting on her relaxed face. She speaks English with a seductive accent. She says: Good morning, I’m Maria, let me explain a few things to you, please pay attention. She looks like she’s not kidding. She’s a representative of the Greek Ministry of Tourism. She specifies that this is neither a game nor a hobby. She explains very seriously that this trip to Mount Athos is like a secret mission, without saying any more about its mysteries and its different stages.

People have been brushing their teeth for 5,000 years. But the universal chore of scrubbing our gnashers twice a day is based on rather whimsical practices.

Consecrated king of hygiene in the 19th century, soap has not always had its place in the learned protocol of bathing....