Snow was swirling against the icy windows once more; Christmas was approaching fast. Hagrid had already singlehandedly delivered the usual twelve Christmas trees to the Great Hall; garlands of holly and tinsel had been twisted around the banisters of the stairs; everlasting candles glowed from inside the helmets of suits of armor and great bunches of mistletoe had been hung at intervals along the corridors. Large groups of girls tended to converge underneath the mistletoe bunches every time Harry went past, which caused blockages in the corridors; fortunately, however, Harry's frequent nighttime wanderings had given him an unusually good knowledge of the castle's secret passageways, so that he was often, without too much difficulty, to navigate mistletoe-free routes between classes.