When Banquo suggests the witches revealed "some truth" to Macbeth, Macbeth said he has not thought of them since in the woods.
The Three Witches or Weird Sisters are characters in William Shakespeare's play Macbeth (c. 1603–1607). Their origin lies in Holinshed's Chronicles (1587), a history of England, Scotland and Ireland. Other possible sources influencing their creation aside from Shakespeare's own imagination include British folklore, contemporary treatises on witchcraft including King James I and VI's Daemonologie, Scandinavian legends of the Norns, and ancient classical myths concerning the Fates, the Greek myths of the Moirai and the Roman myths of the Parcae. Portions of Thomas Middleton's play The Witch were incorporated into Macbeth around 1618.
Shakespeare's witches are prophets who hail the general Macbeth early in the play with predictions of his rise as king. Upon committing regicide and taking the throne of Scotland, Macbeth hears the trio deliver ambiguous prophecies threatening his downfall. The witches' dark and contradictory natures, their "filthy" trappings and activities, as well as their intercourse with the supernatural all set an ominous tone for the play.