True to the witches' formula, Macbeth is both fair & foul and, what is more, he is always conscious of the co-existence of opposites in him. Very early in the play, in act1 sc.3, the fair but ambitious Macbeth admitted in his aside to his 'horrible imaginings' relating to the killing of Duncan. A little later, in act1 sc.7, Macbeth made a highly insightful scrutiny of the thought of murdering Duncan in his soliloquy. The soliloquy shows how Macbeth is fully aware of the pros and cons of the 'deed':
1) No such crime as the assassination of Duncan could by itself 'trammel up the consequence'; punishment will follow crime.
2) Punishment will have to be received here 'upon this bank and shoal of time'.
3) Justice is 'even-handed' and so 'we but teach/Bloody instructions, which, being taught, return/To plague the inventor'.
4) Duncan is his kinsman and his guest, and thus in 'double trust'; his murder would be a violation of the trust of kinship & the trust of hospitality.
5) Duncan has been very transparent in his office of a king & he is virtuous; his killing would invite divine retribution.
6) Macbeth finds no reason to kill Duncan except for his own 'vaulting ambition'.
Let us now examine some of his late responses in ACT 5 when he is a 'tyrant', deserted by his nobles, and strongly opposed by Macduff, Malcolm and others:
a) " I have liv'd long enough: my way of life
Is fall'n into the sear, the yellow leaf:
And that which should accompany old age'
As honour, love, obedience, troops of friends,
I must not look to have........." (act5 sc.3)
Macbeth is tired of his life, as if living on extra time; he knows the autumnal degeneration having set in, and admits that he does not deserve what a good old man hopes to get. He is pitiable, but still self-respecting.
b) " I have almost forgot the taste of fears.
The time has been, my senses would have cool'd
To hear a night-shriek, and my fell of hair
Would at a dismal treatise rouse and stir
As life were in 't. I have supp'd full with horrors. (V.v)
Once again Macbeth is gloomy and introspective, looking back into the past & looking at his present anaesthetised state of mind.
c) " To-morrow, and to-morrow, and to-morrow,
Creeps in this petty pace from day to day,
To the last syllable of recorded time;
And all our yesterdays have lighted fools
The way to dusty death. Out, out, brief candle!
Life's but a walking shadow, a poor player
That struts and frets his hour upon the stage
And then is heard no more; it is a tale
Told by an idiot, full of sound and fury,
Signifying nothing ". (V.v)
The news of Lady Macbeth's death breeds in Macbeth a deep sense of melancholy pessimism, a sense of futility of human life and endeavour. He is more of an existentialist philosopher than a mere tyrant or a killer.
Soon Macbeth goes down to defeat and death, but not without some dignity and self-respect. He refuses to submit to Malcolm and agrees to fight Macduff till death though he realises how the 'juggling fiends' have worked for his undoing.