Macbeth and Banquo encounter three witches on a blasted heath. Both get three prophetic suggestions.
Shocked at the sight of these wizened creatures Banquo asks them, "Live you?" noting that they do not seem to be "Inhabitants o' th' earth." He cannot tell if they are real women or not by the sight of them wearing so much facial hair. Banquo can see Macbeth's fear in reaction to the prophecies and diverts the witch's attention and challenges them "Speak then to me." The witches prophesy that he will not be king, but, his heir's will be kings.
As the witches disappear, both Banquo and Macbeth speculate that the witches were illusory, "bubbles" of the earth, questioning themselves, "have we eaten on the insane root." Although Banquo is tempted by the witch's prophecies, he is far more perceptive and sceptic than Macbeth. He demonstrates a sense of the objective reality of demonic forces and he realises that they are using the doctrine of voluntary accent to entice himself and Macbeth. He tries to convince Macbeth that they might "win us to our harm." He considers them not necessarily to be agents of inevitable fate.
However, Macbeth's integrity has already begun to be undermined. Perturbed and stunned by these "instruments of darkness" Macbeth is speechless for a while, but, then his inquisitiveness gets the better of him. Unable to comprehend how the prospect of his future thaneship and kingship could be reality, he commands the witches to "stay, you imperfect speakers, tell me more," but they just vanish into thin air. .
The king's messengers arrive and the second of the witch's prediction's for Macbeth is confirmed. Macbeth is astonished and again stands wrapped in amazement, unable to speak. He feels elated but then begins to question if the predictions are good, "why do I yield to that suggestion / whose horrid image doth unfix my hair / and make my seated heart knock at my ribs, / against the use of nature?" He feels he is giving into temptation.
