Macbeth Questions

1. (Act IV, i) The witches' pageant provides Macbeth with some important information but in the cryptic form of a prophecy. In other words, it requires interpretation. It is here that we are given the tragic "piece of ignorance" that leads to Macbeth's downfall. Explain.

I don't really understand...what is the tragic piece of ignorance?

2. (Act IV) List some modern day equivalents to Macbeth and his actions.

3. (Act IV) Again, Macbeth has someone else do his dirty work (murder of Macduff's son and Lady Macduff). What do you think makes men willing to commit such appalling brutality in the service of a tyrant?

4. Make a list of symptoms that Macbeth and Lady Macbeth suffer that might indicate psychological problems.

Thanks for your help ^__^
~Lucy