in the beginning he's described as "full of the milk of human kindness", and that means that he was a kind and good man. After hearing the witches prophecy his hunger for power changes him, and he kills the king Duncan. Right after the murder he still shows traces of his old personality: he's regretful, he can't even pronounce the word Murder(he refers to it ad "deed"), and he can't stand to look at Duncan's body. He feels very guilty, and it's almost as if he woshes he hadn't done it. After committing other murders he's completely changed, and at the end he has a monologue, where we can perceive how his emotions have shifted, He says that life is a tale told by an idiot, that it's short and meaningless. He doesn't even have a reaction to his wife's death, he almost seems apathic and detached from reality. He knows that his end is coming.