"My thought, whose murder yet is but fantastical" (1.iii. 152)
Yet do I Fear thy nature: It is too full o' th' milk of human kindness" (1.v.16-17)
The Three Weird Sisters are talking of Macbeth and the day they are to have. As well as their plans for the future
"Art thou afraid to be the same in thine own act and valor as thou art in desire?"(1.vii. 43-46)
Macbeth's first sense of his ambition for murder because he has learned from a prophecy that he will become King. This can also be identified as one of the many motifs of Macbeth's newly found ambition.
"I dare do all that may become a man Who dares do more is none"(1.vii. 51-52)
Lady Macbeth has received news from Macbeth that he is to become Thane of Cawdor and King. She believes that he will somehow ruin it with his inability to hide his emotions.
"False face must hide what the false hart doth know"(1.vii.95-96)
Lady Macbeth threatens Macbeth's manliness in hopes of giving him more motivation to kill King Duncan. She then will be able to manipulate and control him to make the decision she wants.
Macbeth defends himself and says he will be able to do it to prove it to his evil, cruel wife. He says he's ready to do what no other man can.
He needs to be able to disguise his true feelings about the situation as to not ruin their plan that him and his wife discussed. Although he is feeling unsteady inside.