The works of the 14th Century poet Hafez can be found in almost every Iranian home - more than 600 years after his death, the writer still offers an insight into his country's identity.
In Iran they say there are two books in every household - the Koran and Hafez. One is read, the other is not.
To understand this joke you need do no more than join the millions who regularly throng the tomb of Hafez, the 14th Century poet of Shiraz and Iran's national hero, as I did one recent afternoon.