Probably the most frequent question posed by children to their parents.
When we were well into our teenage years my father would, in the style of a politician, always answer that question with a question of his own.
"Why does a dog lick its balls?"
We knew the answer. "Because it can." Discussion over.
I thought of that this morning when at Reverend Green at South Bank.
There I found Sensei Will McLay (on the right) of Happy Dragon Martial Arts and his student Don practising their karate.
I asked Will why he had chosen that spot to go through his paces.
"Because I can," he replied.
Actually, the answer should have been self evident. Would you look at that backdrop? On a fresh Spring morning it would be hard to imagine a better place in the city for morning meditation and exercise.
Sensei Will, Don and sometimes one or two others meet for an hour five mornings a week at this spot for a workout to start the day.
Because they can.
And why not, I say.