Note that in some editions of the play all three witches recite the line Paddock calls: - anon., as we find in the First Folio version. However, this appears to be a Folio misprint, and editor Eugene M. Waith of the Yale Shakespeare rightly breaks up the line and ascribes it to the Second and Third Witches:
Second Witch. Paddock calls. Third Witch. Anon! All. Fair is foul, and foul is fair:
Hover through the fog and filthy air.
"The "Weird Sisters" in Macbeth seem to us neither on the one hand mere mortal witches of popular superstition, nor yet, as Holinshed states, and as their name would imply, do we see in them "goddesses of destiny" -- "fates" determining human actions and issues without regard to that fundamental essence of personality, will. They know the future and can foretell events; yet they are not able of themselves to make those events come to pass." N.B. Bowman. Read on...