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;
And you did so profane me when you crept
Unto the threshold of this room to-night
That I must never more behold your face.
This now is yours. I seek another place.

– Sonnet VI “Bluebeard” from Renascence and Other Poems by Edna St. Vincent Millay

In sooth, I know not why I am so sad:
It wearies me; you say it wearies you;
But how I caught it, found it, or came by it,
What stuff ‘tis made of, whereof it is born,
I am to learn;
And such a want-wit sadness makes of me,
That I have much ado to know myself.

Antonio, The Merchant of Venice 1.1.1-7