What does Macbeth's soliloquy given below in the act 1 scene 7 mean?
"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,(5)
But here, upon this bank and shoal of time,
We'd jump the life to come. But in these cases
We still have judgement here, that we but teach
Bloody instructions, which being taught return
To plague the inventor. This even-handed justice(10)
Commends the ingredients 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,(15)
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(25)
To prick the sides of my intent, but only
Vaulting ambition, which o'erleaps itself
And falls on the other—"
In this soliloquy, Macbeth reviews the many reasons he has not to move forward with the plan to kill Duncan as well as the one reason that he has to actually go through with the murder.
First, he considers that simply committing the murder will not be enough to make him the king: in other words, it will not be "done quickly." He considers the fact that if he could simply commit this one "blow" and achieve his destiny without consequence, it would be a lot easier to go on and risk his eternal soul.
Next, Macbeth considers the fact that, here on earth, there are punishments, consequences for the type of behavior he's considering. For one, when a person commits a violent act, he inadvertently teaches others how to commit violence, and this can come back to harm the initial perpetrator (i.e. him). Though this would be justice, it could spell death for him.
He considers the fact that Duncan is both his relative and his king as well as his guest, and all these relationships should mean that Macbeth actually protects Duncan from violence, not commits the violence himself. Further, Duncan is such a humble, virtuous leader that his legacy would live on and on, and his death will be such a great sorrow to everyone in the kingdom.
Finally, Macbeth claims that he can think of no reason or motivation to kill Duncan aside from his own "Vaulting ambition" which seems to compel him to rush ahead and, perhaps, rush right into danger.
In this monologue, Macbeth thinks about the practical and philosophical issues related to killing King Duncan. He begins by stating that it should be “done quickly” if done at all, showing that he is thinking in detail about how to do the deed. If there were no consequences, Macbeth says, he might be gain great success here on earth, risking “ the life to come.” However, he notes in a later scene that “blood will have blood” and here acknowledges that one can still face punishment in this lifetime. He describes a “live by the sword, die by the sword” mentality, which is exactly what happens: he commits murder after murder and is eventually slain. Macbeth also pities Duncan as a king and a guest. Moreover, Duncan is a good man and leader, and the murder would be a “deep damnation.” Macbeth complains that he has “no spur / To prick the sides of my intent,” comparing his ambition to a leaping horse, but that spur arrives in the shape of his wife Lady Macbeth. She is able to convince him to commit the heinous crime.
This soliloquy demonstrates the inner turmoil Macbeth experiences as he contemplates the murder of Duncan. He recognizes that what he is about to do is morally wrong, not just in the abstract sense, but because Duncan is his kinsman and a guest in his castle. In addition, Duncan is hardly a tyrant. He is a good king, and a good man, and anyone who killed him would be instantly condemned by all who knew him, and ultimately in the eyes of God. Macbeth recognizes, then, that he has no moral justification for assassinating Duncan. He is driven only by "vaulting ambition" to fulfill what he sees as his destiny. This is Macbeth's mental state when he encounters his wife, who then fortifies his courage, challenging his masculinity in an attempt to get him to overcome his scruples and achieve his destiny.