Poetry is an impossible device. No matter how you want it, it is never fit for something like a marble tablet. It is more like a varied mountain range, emerging from the cauldron to stand around the crater. While it does have a historical link with its erratic source, it has its own distinct shape as well. It might appear stationary but actually it is not. From it, people — readers, that is — can make a sculpture without changing the basic shape of the stone. Or build a rock garden.