What does this phrase mean from macbeth?

Question: What does this phrase mean from macbeth!?

"What's fair is foul, What's foul is fair"

what does this phrase mean!? i've seen this phrase on a e-card on the otaku!.com and i was just wondering what it meant!. and dont get me wrong, but i have had reading classes before and we have read macbeth and we also did a play on it!. and so i was just wodering what the phrase meant!. So, can anyone please tell me!? Www@QuestionHome@Com

Best Answer - Chosen by Asker:

"Fair is foul, and foul is fair!." The three witches say that line in the first scene of "Macbeth!." "Fair" in this context means good and beautiful, while "foul" means evil and ugly!. The witches are saying that what others think of as good is evil to them and what others think of as evil is good to them!.Www@QuestionHome@Com