InMacbethby William Shakespeare, Act IV, scene 1 begins with the witches' preparation of a magic potion. When Macbeth arrives, he wishes to find answers to the witches' prophecies, calling for them to reveal their sources: "Call 'em, let me see 'em!" (68)
The first apparition appears as an armed head, who "knows thy thought" (69). According to the first witch, the apparition has the gift of mind-reading. The armed head warns Macbeth "beware of Macduff, beware the thane of Fife" (78-80).
Macbeth is thankful, but curious. The head "has harped [Macbeth's] fear aright" (82). His hopes of asking another question are dashed by the first witch who tells him, "he will not be commanded" (83).