They had moored their boat one night under a bank veiled in high grasses and short pollarded trees.  Sleep, after heavy sculling, had come to them early, and by a corresponding accident they awoke before it was light.  To speak more strictly, they awoke before it was daylight; for a large lemon moon was only just setting in the forest of high grass above their heads, and the sky was of a vivid violet-blue, nocturnal but bright.  Both men had simultaneously a reminiscence of childhood, of the elfin and adventurous time when tall weeds close over us like woods.  Standing up thus against the large low moon, the daisies really seemed to be giant daisies, the dandelions to be giant dandelions.  Somehow it reminded them of the dado of a nursery wall-paper.  The drop of the river-bed sufficed to sink them under the roots of all shrubs and flowers and make them gaze upwards at the grass.  “By Jove!” said Flambeau, “it’s like being in fairyland.”

Father Brown sat bolt upright in the boat and crossed himself.  His movement was so abrupt that his friend asked him, with a mild stare, what was the matter.

“The people who wrote the mediaeval ballads,” answered the priest, “knew more about fairies than you do.  It isn’t only nice things that happen in fairyland.”

“Oh, bosh!” said Flambeau.  “Only nice things could happen under such an innocent moon.  I am for pushing on now and seeing what does really come.  We may die and rot before we ever see again such a moon or such a mood.”

“All right,” said Father Brown.  “I never said it was always wrong to enter fairyland.  I only said it was always dangerous.”

They pushed slowly up the brightening river; the glowing violet of the sky and the pale gold of the moon grew fainter and fainter, and faded into that vast colourless cosmos that precedes the colours of the dawn.  When the first faint stripes of red and gold and grey split the horizon from end to end they were broken by the black bulk of a town or village which sat on the river just ahead of them.  It was already an easy twilight, in which all things were visible, when they came under the hanging roofs and bridges of this riverside hamlet.  The houses, with their long, low, stooping roofs, seemed to come down to drink at the river, like huge grey and red cattle.  The broadening and whitening dawn had already turned to working daylight before they saw any living creature on the wharves and bridges of that silent town.  Eventually they saw a very placid and prosperous man in his shirt sleeves, with a face as round as the recently sunken moon, and rays of red whisker around the low arc of it, who was leaning on a post above the sluggish tide.  By an impulse not to be analysed, Flambeau rose to his full height in the swaying boat and shouted at the man to ask if he knew Reed Island or Reed House.  The prosperous man’s smile grew slightly more expansive, and he simply pointed up the river towards the next bend of it.  Flambeau went ahead without further speech.