The child is meant to represent Malcolm, son of King Duncan, and the tree in his hand shows how his army will camouflage itself as it approaches Macbeth's castle. But this meaning is lost on Macbeth, and he believes he is safe when the Apparition says that "Macbeth will never be defeated until the wood of Great Birnam and the high hill of Dunsinane come against him." (Shakespeare 64). He was exultant because he was sure that trees cannot walk, and he knows that the forests of Birnam Wood cannot move or walk to Dunsinane Hill. Maybe Hecate and the three witches will make a natural move or maybe they will make a big storm and move