The three apparitions tell Macbeth to beware Macduff, no man born of woman can harm him, and that he is safe until the forest comes.
Macbeth is starting to feel uneasy at the end of Act 3. He decides he needs to confer with the witches. This time, Hecate is involved—the stakes are higher. Macbeth is greeted by a series of apparitions, and each one has an important message for him.
First, an “armed head” warns Macbeth:
Macbeth! Macbeth! Macbeth! Beware
Beware the Thane of Fife. (Act 4, Scene 1)
Macbeth thanks them for the warning, but is not concerned. He feels like he can handle Macduff.
Second, a “bloody child” assures Macbeth:
Be bloody, bold, and resolute; laugh to
The power of man, for none of woman born
Shall harm Macbeth. (Act 4, Scene 1)
Macbeth is satisfied with this answer. He figures that he must be safe, because every man was born of a woman. Yet this apparition seems to contradict the last apparition that told him to beware Macduff.
Third a “crowned child” promises that:
Macbeth shall never vanquish’d be until
Great Birnam Wood to high Dunsinane Hill
Shall come against him. (Act 4, Scene 1)
Macbeth is confused. After all, how could a forest come to him? He must be safe.
The warnings all come true, but not in the way Macbeth expects. The forest does come, because Malcolm has the soldiers pretend to be trees by carrying branches. When he find out that Macduff was born of C-section, and therefore not technically born of a woman, he feels deflated. He gives up.