In Act 1, Scene 7, Macbeth seems cowardly to Lady Macbeth because he wants to back out of killing King Duncan. She gets ruthless by emasculating him and comparing him to a feminine image of a feline who wants to go get some fish, but refuses to get a little bit wet in the process. He responds by telling her to be quiet and defends himself by saying, "I dare do all that may become a man;/ Who dares do more is none" (I.vii.46-47). She goes on for another long bit of dialogue condemning him and saying that she's manlier than he is because she'd kill her own baby if it suited her purposes. Macbeth cowers to her and asks what will happen if they fail in their goal. At that point, he is in her power.