Soliloquy # 3 Act 1 Scene 7.

MACBETH:
If it were done when 'tis done, then 'twere well
It were done quickly: if the assassination
Could trammel up the consequence, and catch
With his surcease success; that but this blow
Might be the be-all and the end-all here,
But here, upon this bank and shoal of time,
We'ld jump the life to come. But in these cases
We still have judgment here; that we but teach
Bloody instructions, which, being taught, return
To plague the inventor: this even-handed justice
Commends the ingredience of our poison'd
Chalice To our own lips. He's here in double trust;
First, as I am his kinsman and his subject,
Strong both against the deed; then, as his host,
Who should against his murderer shut the door,
Not bear the knife myself. Besides, this Duncan
Hath borne his faculties so meek, hath been
So clear in his great office, that his virtues
Will plead like angels, trumpet-tongued, against
The deep damnation of his taking-off; 20
And pity, like a naked new-born babe,
Striding the blast, or heaven's cherubin, horsed
Upon the sightless couriers of the air,
Shall blow the horrid deed in every eye,
That tears shall drown the wind. I have no spur
To prick the sides of my intent, but only
Vaulting ambition, which o'erleaps itself
And falls on th'other.




If I have to kill him, it's better that it's done quickly. If the assasination could prevent all the consequences, then it will be-all and end-all. But here in this time we would skip our after life. In this case we still have judgment, we are taught to kill by the king, and are being taught to kill the king. This even justice praises the quality of our poison we are about to drink (Justice would think it's good that we are about to kill Duncan. That Macbeth deserves to be king, that the king's death would be justice for any wrong-doings Duncan did.) I am stuck in a difficult place, I am trusted by the king in two ways at this point, first as his kinsman and a subject of his ruling power, any other person like me would be against killing him. Second, I am his host, who should protect the King of a killer, not be the killer myself. Duncan has made his power so weak, has been so clear in his ruling that his courage will plead like strong angels against the killing. Will make us feel pity, like a new born baby. The news of killing the king will be spread around to everyone like it was floating in the wind, and that tears will stop the wind. I have no reason to kill the king (Nothing against him) only my ambition to be king myself, which overpowers any reason and falls on the other side of wanting to be king myself.

In this he is making the decision to kill the king because he wants to be king, not for any dislike for the king.