What are some important lines in Act 2 Scene 2 of Macbeth?Really anything important that has an impact on the play such as foreshadowing,...

In Act 2 Scene 2 of Macbeth, Lady
Macbeth has drugged the guards and is waiting to see if Macbeth follows through with the
murder.  While she waits, she hears an owl shriek and calls it the "fatal bellman." 
This symbol suggests that the murder has taken place.  Shortly after, Macbeth returns to
their chamber crazed because he believes that someone has heard him commit the murder. 
Lady Macbeth is angry with him because he cannot control his emotions, and she tells him
that she would "shame to wear a heart so white."  This element of characterization
suggests that Macbeth is weak at heart.  Finally, at the end of the scene, Macbeth and
his wife hear knocking at the door.  Macbeth says that he wishes the knocking would wake
Duncan which suggests that Macbeth feels regret for what he has
done.