midnight
The Doctor sighed and watched the pageant of light until it faded and the stars lit up the magical blue darkness . Then out of the night came another song -- a song which seemed familiar to the Doctor , although for the moment he could not place it , about a King in the Northern Country who was faithful to the grave and to whom his dying mistress a golden beaker gave . `` Strange , '' thought the Doctor , `` it must come from some Northern fishing smack , '' and he went home . He sat reading in his study until midnight , and for the first time in thirty years he could not fix his mind on his book . For the vision of the sunset and the song of the Northern fisherman , which in some unaccountable way brought back to him the days of his youth , kept on surging up in his mind . Twelve o'clock struck . He rose to go to bed , and as he did so he heard a loud knock at the door .