Because of the three witches' stong mental abilities the play was foreshadowed through their prophecy. The crystal ball shows their ability to predict the future. They were able to see what was going to happen to Macbeth through using their gifted mental abilities.
Which New "Doctor Who" Companion Are You? ~ I'm Amy Pond! The girl who waited! Feisty, flirtatious, and ultimately one of the Doctor’s most loyal companions. You enjoy seeing and trying new things, and you don’t like to sit still for long.