In I. v., having received Macbeth's letter describing his encounter with the witches and their prophecies, Lady Macbeth is further notified that Duncan will spend the night. It is at this point that she decides two things: Duncan must die and Macbeth must be bolstered to perform the act. How can she achieve this? She calls upon "you spirits," perhaps the Evil Spirit himself or his "murdering ministers" who specialize in transforming humans to do evil acts with impunity. "Unsex me here..." Destroy within me all the goodness associated with my feminine nature, my tendencies to sympathize, to feel remorse, to mother and to nurture. In brief, make me a witch. Secondly, she calls upon the night to hurry and provide them cover with the "smoke of hell" to conceal from heaven the horrid act of murdering Duncan.