A moment later the exquisite, smoothly rippling music which he had himself written for the Swan-Maiden dance purled out into the room.
The story of the Swan-Maiden had been taken from an old legend which told of a beautiful maiden and the youth who loved her.
According to the narrative, the pair were unfortunate enough to incur the displeasure of the evil fairy Ritmagar, and the latter, in order to punish them, transformed the maiden into a white swan, thus separating the hapless lovers for ever.

Afterwards, the disconsolate youth, bemoaning the cruelty of fate, used to wander daily along the shores of the lake where the maiden was compelled to dwell in her guise of a swan, and eventually Ritmagar, apparently touched to a limited compassion, permitted the Swan-Maiden to resume her human form once a day during the hour immediately preceding sunset.

But the condition was attached that she must always return to the lake ere the sun sank below the horizon, when she would be compelled to reassume her shape of a swan.

Should she fail to return by the appointed time, death would be the inevitable consequence.
Every reader of fairy tales--and certainly anyone who knows anything at all about being in love--can guess the sequel.

Comes a day when the lovers, absorbed in their love-making, forget the flight of time, so that the unhappy maiden returns to the shore of the lake to find that the sun has already dipped below the horizon.