If you're so smart, how come your hat's on back to front?

"SEE THAT report in the paper about the mice?" said the man at the bar.

When people in pubs ask questions like that, they do not require an answer. They are merely announcing that they are about to tell you all about it, and are requesting a gap in the conversation, rather like a motorist signalling to pull out.

"What mice were they then?" said the man with the dog, courteously slowing down and letting him have access to the flow of talk.

"Californian mice," said the man at the bar. "Apparently some scientists in California have shown that jogging is not just good for the body, it's also good for the mind. People who take exercise have their mental faculties sharpened at the same time as their physical fitness is improving."

"So, where do mice come into this?" said the resident Welshman, speaking, I think, for all of us.

"Because the scientists did all the experiments on mice," said the man at the bar.

There was a pause.

"How did they get the mice to go jogging?" said the resident Welshman, and again I think he spoke for all of us.

"How far did they have to run?" said the lady with orange hair, sipping her orange juice.

"Being Californian mice, did they all wear tiny baseball caps turned backwards?" said the man with the dog.

"As they jogged, did they listen to tiny Sony Walkmans?"

"Or Sony Walkmice?"

"And were they sponsored by Nike or Adidas?"

"Listen!" said the man at the bar. "All I know is that they did the experiments on mice! It doesn't say what the experiments were. But it cannot be beyond the wit of man to devise an experiment which exercises a mouse without making him wear tiny trainers. A treadmill, for example. An exercise wheel..."

"How cruel," said the orange lady. "Humans jog voluntarily. Why make mice do it compulsorily?"

"If I were a laboratory mouse," said the man at the bar, "I'd rather do a bit of exercise than smoke cigarettes or wear lipstick. Anyway, it's quite possible that exercise does sharpen your thinking."

"If that were true," said the Welshman, "then footballers and athletes would be the best debaters, and Jeremy Paxman and Melvyn Bragg would be tongue-tied."

"I believe Melvyn Bragg plays football occasionally," said the orange lady, "and Jeremy Paxman is said to be very fond of fishing."

"Lot of bloody exercise you get fishing," said the Welshman. "Can you imagine Paxman striding up and down as he fishes? I think not."

"Can you imagine Paxman interrogating the fish?" said the man at the bar. "Can you imagine him turning a beady eye and a curled lip on a bream and saying: `Are you really trying to tell me that a bream like you, and thousands of bream in the same position, intend to hold the country to ransom by deliberately not taking my bait? That seems a pretty poor show to me...' "

There came one of those pauses when everyone realises the conversation is in a cul-de-sac.

"I tell you what," said the orange lady, reversing sharply and rejoining the main road, "if jogging gave you increased mental ability, it would stop you jogging."

"How'd you reckon that?"

"Well, the more you jogged, the more you'd see things clearly, and you'd see clearly that jogging is bad for you. All that pounding on the road messes up your joints. You breathe in polluted air. You tend to get run over. Bad for you. As your brain got sharper, you'd see that. You'd give up."

"If you followed that argument through," said the man with the dog, "you'd then lose your mental sharpness after you'd given up. And then you'd forget why you'd given up and take up jogging again."

"It must be incredibly boring, jogging," said the orange lady. "Otherwise why would they listen to music on those headphones?"

"You don't know it's music. Might be story tapes. Might be Shakespeare. Might be Schopenhauer. Might be proof that jogging does sharpen the brain!"

"I had a hamster once," said the man who normally never spoke. "It lived in a cage and it had an exercise wheel. For a long time it never got on the wheel, then one day it got on and seemed to like it, because after that it increased its occupancy of the wheel and sometimes did four or five hours a day. It's my belief that all this exercise must have sharpened its mind, because one day we found the cage empty and the hamster gone. It had worked out how to open the door by itself. It had never been able to do that before it started jogging."

That seemed to settle the subject, so we all talked about something quite different.