A Room and a Riddle

So: the candle has passed through a portal
Stayed by a sentry as I try to follow
Changing my cloak to a gown to gain entry
There in the center its bearer awaits
In a circular chamber of doors
Guarded by shadowy forms
There in the middle; a room and a riddle She fades away…
There where she was
A golden bird did appear
Briefly I heard the song of that bird
And then it too disappeared
Traded my cloak for a gown; look around It’s the same as these guardians wear
Faces obscured, still undisturbed With their doors in this circular lair
The silence eventually broke
In one voice, the guardians spoke
There in the middle; a room and a riddle Surrounded thus
«An oath to be sworn and a robe to be worn
Now you’re one of us!»
Sentries and doors!
Guard with your life
Behind each door:
A withered child clutching a knife