In Macbeth, what are some examples of the relationship between cruelty and power in Lady Macbeth and Macbeth?

If I were you, I would want to start off by looking at the
famous scene where Lady Macbeth harangues her husband into sticking to his intention of
killing Duncan in Act I scene 7. This is a very interesting scene to analyse, as she
uses a number of different techniques to persuade her husband to do what she wants him
to do, and in particular we can see how power and cruelty intersect through her power
over her husband and some of the methods that she uses to manipulate
him.

It is clear that at the beginning of the play at
least, Lady Macbeth has power over her husband. She is cruel in the way that she
intentionally mocks and shames her husband by arguing that it is cowardice that prevents
him from putting his words into actions:

readability="19">

Art thou afeard

To
be the same in thine own act and valour,

As thou art in
desire? Would'st thou have that

Which tou esteem'st the
ornament of life,

And life a coward in thine own
esteem,

Letting "I dare not" wait upon "I
would,"

Like the poor cat
i'th'adage?

Note how she
questions her husband's "manhood" in this passage, cruelly goading him on to doing the
act that he does not wish to do. She continues by creating an incredibly cruel image of
her dashing the brains of her baby out against a wall rather than break her promise.
Thus we can see that there are definite examples of cruelty in her relationship with her
husband and how she maintains her power over him.