I just looked at the surrounding lines. This is when Macbeth and others are discussing Duncan's murder.
Macbeth reveals that he killed Duncan's alleged assassins (the servants/guards), and Macduff asks him why ("Wherefore did you so?").
Macbeth responds with
"Who can be wise, amazed, temperate and furious,
Loyal and neutral, in a moment? No man:"
Basically, Macbeth is saying that he was in such an emotional rage at seeing Duncan dead that he couldn't control himself. He is a wise person
He was amazed at seeing Duncan dead
Being temperate would involve virtually no reaction to the murder
but he was furious at the thought of Duncan's murderers being right there
So, Macbeth says that Macduff can't have expected Macbeth to remain calm and not act, and that it was natural for Macbeth to kill Duncan's alleged murderers in a situation like that.
(Don't forget though, the servants didn't actually kill Duncan =P)
· 1 decade ago