It's a strange time to be writing about Christmas. But one of the magical things about Christmas is that it is a festival that really does mediate joy. Even as I write, the occasional glimpse of Christmas goods in the shops, the family Christmas plans that necessarily need to be made in advance, the rich smell of the Christmas cake in the oven, and even a few early Christmas carols all have the old power to recall all the Christmases you ever experienced, and for those of us who are Christians, to turn our thoughts once again to our Saviour's birth.