In Jerusalem, stones can do the work of flowers – at Jewish cemeteries, that is, where flowers on graves are taboo. To show you have been at a graveside you place a pebble or a chip or a rock on the gravestone. Then you inspect the rows nearby to see how their little piles measure against yours. A spirit of sporting rivalry adds a little spice to a sad occasion, and people play, I think, according to the rules. They don’t pile stones greedily; one a piece and no cheating. It’s a matter of respect.