Prophecies in tragedies

I was certain I was not the only one who had realized that the first prophecy was a set up for the entire plot. The storyline in Macbeth would not have moved pass act 1 scene 2 if Macbeth and Banquo had not eavesdropped on the three witches’ gathering. Unlike the other prophecies in act 4, the very first one is a self fulfilling prophecy. Macbeth did not sit back and wait to name King, he took charge of the matter. Similar to Oedipus the King, he meddled with his fate and that probably caused his downfall. I can’t help but wonder if the prophecy caused the actions or the actions were to be predicted. In both Macbeth and Oedipus the King the revelations seem to provoke the actions especially in Macbeth where the witches appear to be maleficent and may have orchestrated his despair. Prophecies in tragedies are ambiguous which would also explain why our tragic heroes have falling to their death so ironically. Macbeth was not told how he would be King? Nor was he to know that MacDuff “was from his mother’s womb/untimely ripped” (5.8.19-20). No wonder Macbeth thought he was invincible. One thing for sure, knowing what the future has in store for us can be very dangerous.