"Whose horrid image doth unfix my hair, And make my seated heart knock at my ribs, Against the use of nature?"
The quote from Macbeth reflects his internal conflict after hearing the witches' prophecies. His heart pounding and hair standing on end symbolize his fear and anxiety at the thought of committing murder to fulfill the prophecy of becoming king. Despite the horror this idea induces, it's evident his ambition is considering this dreadful act, indicating the start of his destructive path.