There are only two characters in the play who are strongly motivated by ambition. They are Macbeth and his wife. Of the two it is Lady Macbeth who displays the most evil and cruel ambition. She goads her husband into murdering King Duncan. Without her relentless urging, Macbeth would have changed his mind. He can think of many reasons for not killing Duncan but nothing to make him commit the crime except "vaulting ambition." Lady Macbeth is actually an accomplice. She drugs Duncan's two attendants and then takes the daggers back to the King's chamber to smear the attendants with blood and leave the murder weapons as evidence against them. After Duncan's body has been discovered, she keeps advising her husband how to behave. (She tells him, "Look like the innocent flower, but be the serpent under it." She is describing herself and her own modus operandi.) Shakespeare evidently did not want Macbeth to be a complete villain like Richard the Third, so he placed some of the blame for Macbeth's actions on his wife as well as on the three witches.