What are some examples of dark imagery in Macbeth?

In William Shakespeare's Macbeth the
ambition for power leads to the dark and mysterious realm of
witchcraft, murders, insomonia, and madness.  And, the imagery used to inspire the
experiences of darkness and evil are abundant.

Certainly,
the weather connotes sinister acts. For instance, the play opens with "fog and filthy
air" as the three witches stir their cauldron and the captain describes the actions of
the dauntless Macbeth:

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For brave Macbeth--well he deserves that
name--

Disdaining fortune, with his brandished
steel,

Which smoked with
bloody execution.
(1.2.16-19)

And, throughout
the play there are storms, dark castles in which the candles are out (2.2,5), and
murders in the night. As Lady Macbeth prepares to "unsex" herself in order to encourage
Macbeth in his deadly deeds, she asks that heaven not "Peep through the blanket of the
dark" (1.53)

Enthralled by the prophecies of the
"instruments of darkness" as they win him with "honest trifles," Macbeth spends many a
night of "curtained sleep" (2.2.51).

When Macduff and
Lennox arrive at Macbeth's castle in Act II, Scene 3,  Lennox describes the night as
"unruly," speaking of confusion.  He describes the earth as shaking the livelong
night."  Ironically, Macbeth agrees, "'twas a rough night"
(2.3.63).

The many dark images of night and its
predominance in the play clearly suggest that evil
abounds:

That
darkness does the face of earth entomb.
(2.4.

Banquo says in Act III
that he

must
become a borrower of the
night

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For a dark hour or
twain.(3.1.27-28)

And, as he
sends his murderers to kill Banquo, Macbeth comments,

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Good things of day begin to droop and drowse
(3.3.53)

In Act IV, Malcolm,
determined to return to Scotland tells Macduff, "The night is long that never finds the
day" (4.3.240). And, so it is for Macbeth whose many nights of murder have finally
caused the madness of Lady Macbeth as well as that of Macbeth
himself.