they started to concentrate themselves in the centre of the room , and there seemed to be a kind of charge running through them , with flashes here and there , as if small electrical storms raged inside the cloud of feathers- a spasm surged through the cloud , every bit of feather rushing towards a middle point- where , for the briefest of seconds , the feathers came together to make a great white bird , its wings outstretched , its neck unfurling high into the air , its head curled back in what might be ecstasy , might be terror , might be fury or sorrow- and then it blasted apart , uncountable feathers and sparks flung across the room as it exploded- the sparks caught cloth and books and wood and curtains as they landed in a hundred different spots , igniting them- the fire began like this ( 4 ) .