Fair is Foul and Foul is Fair...the witches lines.

Macbeth' s first words are similar. He says "So foul and fair a day I have not seen."

How can bad be good and good be bad?

When Macbeth meets the "weird sisters", they tell him he will be king.
Do you think this infuences his thoughts? Has he been infected by the seeds they plant with their words? Are the witches capable of changing destiny, or is Macbeth simply ambitious from the beginning?