The Weird Sisters' prophecies

The sisters prophecies where for the most part accurate but did not tell the whole truth. Like when the witches told Macbeth that no man born of woman will harm him, but that there will be a man born from a sea-section will come to defeat Macbeth. Or even when they talk about the forest moving in towards them, we think it will never happen but does because they use the branches and what not as disguise. I believe weather or not the witches told there prophecies and what they left out nothing would have changed and ended like it did. I feel there is nothing you can do to change the future and was meant to happen.