There’s an old joke about a Jewish passenger on a cruise ship that sinks. The passenger, let’s call him Mr Cohen, manages to swim to a nearby desert island, where he sets up home and waits to be rescued. Life is not too bad; there is a plentiful supply of food and water. Several years later another ship finally arrives. The captain asks what the two buildings on the island are. 

‘Synagogues’, replies Mr Cohen.

‘But you are alone. Why do you need two synagogues when there is only one of you?’

‘The one on the right is the synagogue that I pray in’, says Mr Cohen. ‘And the other one, I’ll never