My hands are of your colour but I shame to wear a heart so white; I have almost forgot the taste of fears ... I have supp'd full of horrors.; Out, out, brief candle! Life's but a walking shadow ... signifying nothing.
In scene 3 it is revealed that they are truly evil. The witches prophesied that Macbeth will be the Thane of Cawdor and the King of Scotland. They prophesied Banquo's children will be kings of Scotland.