After reading Shakespeare's play Macbeth, outline the reasons Macbeth offers as to why banquo must be killed. What else does Macbeth's soliloquy...

In act 3, scene 1 of Shakespeare’s play
Macbeth, the title character offers a number of reasons to justify
the killing of his friend Banquo. Among those reasons are the
following:

• Because of the witches’ prophecy that
  Banquo’s descendants will become kings of Scotland, Macbeth cannot feel entirely safe as
  king until Banquo and Banquo’s son are killed (“To be thus [that is, king] is nothing,
  but [that is, unless] safely thus” (3.1.48).


• Banquo’s
  character is so inherently noble that he may prove more popular and admired than Macbeth
  and thus be a threat to Macbeth’s power:

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. . . in his royalty of nature reigns
that

Which would [that is, must] be feared
(3.1.50-51)

• Banquo
  is not only a good man but a daring, brave, wise, and prudent man who knows how to act
  in his own best interests – interests that may not coincide with the interests of
  Macbeth (3.1.51-54).


• Banquo’s responses to the witches
  suggest that Banquo may have ambitions of his own which might conflict with the
  ambitions of Macbeth (3.1.57-59).


• The witches had “hailed
  [Banquo as a] father to a line of kings” (3.1.60). In contrast, their prophecies
  regarding Macbeth’s power had been limited and equivocal
  (3.1.61-64).


• If the prophecy concerning Banquo is true,
  then Macbeth has killed Duncan to benefit Banquo – an outcome Macbeth wants to prevent
  (3.1.64-70). Macbeth may thus go to hell only to benefit Banquo, a prospect that Macbeth
  cannot accept.

When the two murderers appear,
Macbeth offers even further reasons for killing Banquo, including the
following:

• Macbeth claims that Banquo has
  opposed the good fortune of the murderers (3.1.76-78). He thus pretends that killing
  Banquo is in their own best interests.


• Macbeth claims
  that although he could easily banish Banquo,
  

.
. . yet I must not,

For [that is, because of] certain
friends that are both his and mine,

Whose loves I may not
drop . . . . (3.1.121-22)

In
other words, it would not be politically prudent for Macbeth to banish Banquo, and so
Banquo must be killed.

• Finally, Macbeth mentions
  “sundry weighty reasons” for wanting Banquo killed (3.1.126), which may include some of
  the reasons already mentioned above.

In this
scene, Macbeth reveals himself as jealous, envious, fearful, insecure, vengeful, and
conniving – not an attractive picture at all.