Macbeth Act 3, Scene 2

Macbeth is thinking he will be successful at cheating the system. He is confident that after Banquo and his son are dead his worries will be dramatically less. He doesn't seem to have any guilt for what he wants done. This is quite different from his attitude before he killed Duncan. He thinks that because he is king now there isn't anything he can't get away with. He also believes that the only way for him to live in peace is to eliminate his enemies, which happen to be Banquo and his son.