The Banquo Soliloquy

Act 1: Scene 3: Lines 126 - 142

(aside)      Two truths are told,	The witches said two things that are true,
As happy prologues to the swelling act	as a happy beginning would lead in to a happy ending
Of the imperial theme. (to ROSS and ANGUS) I thank you, gentlemen.	of myself becoming king. Thank you for this news!
(aside) This supernatural soliciting	This supernatural interest in my life
Cannot be ill, cannot be good. If ill,	can neither be particularly good, nor particularly bad.
Why hath it given me earnest of success,	If bad, why would it bode good news,
Commencing in a truth? I am thane of Cawdor.	being rooted in fact? I am now Thane of Cawdor, this much is true.
If good, why do I yield to that suggestion	But if it were good, why do I dread yet accept
Whose horrid image doth unfix my hair	the terrible thought of killing the king? It makes my hair stand on end,
And make my seated heart knock at my ribs,	and my heart race
Against the use of nature? Present fears	despite no present danger. This fear
Are less than horrible imaginings.	though just a thought,
My thought, whose murder yet is but fantastical,	is a thought so far beyond my usual thinking
Shakes so my single state of man	that it renders me unstable.
That function is smothered in surmise,	I can only speculate,
And nothing is but what is not.	and am incapable of function besides entertaining these thoughts.

Macbeth, in this soliloquy, first begins to think of such an evil act as regicide as possible, and has been cited by Wilson Knight as "the birth of evil in Macbeth." (Pg 16, Macbeth by William Shakespeare). This aside illustrates the conflict in Macbeth's mind that renders him so indecisive. He is trying to weigh whether the ascension to king is really worth killing Duncan for?