This door you might not open, and you did;
So enter now, and see for what slight thing
You are betrayed…. Here is no treasure hid,
No cauldron, no clear crystal mirroring
The sought-for truth, no heads of women slain
For greed like yours, no writhings of distress,
But only what you see…. Look yet again--
An empty room, cobwebbed and comfortless.
Yet this alone out of my life I kept
Unto myself, lest any know me quite;
Edna St. Vincent Millay uses punctuation and breaks in the narrative in the this final line before the volta to increase a sense of suspense within the poem.
Bluebeard Sonnet VI