My mother had a maid call’d Barbara
She was in love; and he she lov’d prov’d mad,
And did forsake her: she had a song of Willow,
An old thing ‘twas, but it express’d her fortune,
And she died singing it: that song to-night
Will not go from my mind; I have much to do,
But to go hang my head all at one side,
And sing it like poor Barbara.

—Desdemona, OTHELLO, Act IV, SC III

Glamis thou art, and Cawder; and shalt be
What thou art promis’d.—Yet do I fear thy nature:
It is too full o’th’milk of human kindness,
To catch the nearest way. Thou wouldst be great;
Art not without ambition, but without
The illness should arttend it:
Hie thee hither,
That I may pour my spirits in thine ear,
And chastise with the valour of my tongue
All that impedes thee from the golden round,
Which fate and metaphysical aid doth seem
To have thee crown’d withal.

—Lady Macbeth, MACBETH, Act I, SC V

How, then, am I mad? Hearken!
and observe how healthily—how calmly
I can tell you the whole story. It is impossible
to say how first the idea entered my brain;
but once conceived it haunted me day and night.
Object there was none. Passion there was none.
I loved the old man. He had never wronged me.
He had never given me insult. For his gold
I had no desire. I think it was his eye! yes,
it was this! One of his eyes resembled that of a vulture—
a pale blue eye, with a film over it.
Whenever it fell upon me, my blood ran cold;
and so by degrees—very gradually—
I made up my mind to take the life of the old man,
and thus rid myself of the eye forever.

—The Madman, THE TELL-TALE HEART