act 3 scene 4

The Ghost comes to warn Hamlet of his promise not to contrive against his mother. He interrupts Hamlet's rant against his mother. This is significant to Hamlet's character. Hamlet had obsessed about his mother through the book. Many critics imply a Freudian complex Hamlet might have. It takes the Ghost's re-visitation to remind Hamlet that this story is supposed to be about revenge against Uncle Claudius.