There is a staircase in Rome made of wood, now polished to a shine and worn down by the pilgrims who ascend it on hands and knees. They climb the steps in slow procession, pausing to cry and whisper at each rise and tread. I once walked up those stairs, some twelve years ago, up between those huddled figures, to stand on the landing and watch the pilgrims move towards me like a slow, black river running uphill. At the time, I neither counted the steps nor considered their significance.