In Macbeth, what did the witches tell Macbeth would have to happen before he was harmed?Something about the forest coming into town and there were...

Macbeth decides to visit the witches to get more
information on his future and whether or not there are any threats to his position as
king.  When he arrives, the witches conjure three apparitions that speak to Macbeth
about his future.  The first apparition tells him to beware Macduff.  The second tells
him that none of woman born shall harm him.  The third apparition tells Macbeth that he
should not fear until Birnam wood come to Dunsinane hill.  From these apparitions,
Macbeth knows that Macduff is a threat to him, so he hires more men to murder Macduff's
family, not knowing that Macduff would not be present.  Macbeth also misinterprets the
words of the other apparitions and assumes that they are not logical and could never
come true, after all, the forest cannot "walk" and everyone was born from a
woman.