The Greengrocer Who Chalks a Riddle Every Morning

Outside the greengrocer's on Larch Street stands a wooden chalkboard, the folding kind that most shops use for prices. Mr Okafor has never written a price on it. Every morning at seven, before the first crate of pears is carried out, he wipes it clean with his sleeve and chalks up a riddle instead.

The rules are older than most of his customers. The riddle stays up all day. Nobody is told the answer before closing time, not the postman, not the bus driver, not the woman from the bakery who has tried bribing him with warm rolls. If you think you have it, you whisper it across the counter while he weighs your potatoes. A right answer earns a nod and one free apple. A wrong one earns a kind shake of the head and, somehow, also an apple.

So the whole street spends its day thinking. The bus queue argues about it. The hairdresser asks every customer under the dryer. Two retired teachers, who have not agreed on anything since 1998, meet on the bench at eleven to compare notes, and they have been known to share a flask of tea when a riddle is particularly hard.

Then, one wet Thursday in November, the board was empty. Mr Okafor was away at his sister's wedding, his first day off in eleven years, and his nephew had opened the shop without knowing about the chalk. By nine o'clock people were standing in front of the blank board as if a bus had failed to come. The hairdresser said the street felt like a clock with no hands.

It was a girl of nine called Nell, on her way to school, who picked up the stub of chalk from the ledge. She thought for a moment, stood on tiptoe and wrote, in large careful letters, a question: what gets wetter the more it dries? Then she went to school. The street breathed out. The bus queue started arguing. The two teachers were on the bench by eleven.

When Mr Okafor came back on Friday, the riddle was still there, with one word chalked small underneath by his nephew at closing time, as the rules require: a towel. He read it twice. Then he fetched a second, smaller chalkboard from the back room and hung it at the height of a nine-year-old. Thursdays now belong to guest riddles. Nell has set a good many since, and the grown-ups have solved fewer of them than they like to admit.

The real idea behind it

A riddle is a tiny problem with a guaranteed answer, and that is a rare and comfortable thing. Most of the questions in a day have no neat solution waiting at closing time. A riddle does, and working on one together gives people who would otherwise only nod at each other a reason to talk.

That is why small shared puzzles turn up wherever people pass each other every day: the quiz question on a café board, the brain-teaser pinned up in a staff room, the joke a baker writes on the paper bag. None of them is important. Each one quietly says that somebody here is thinking of you, and that for the price of a guess you are welcome to join in.