Which theme is used in this excerpt from act I of Shakespeare’s Macbeth?
 LADY MACBETH:
 O, never
 Shall sun that morrow see!
 Your face, my thane, is as a book where men
 May read strange matters:—to beguile the time,
 Look like the time; bear welcome in your eye,
 Your hand, your tongue: look like the innocent flower,
 But be the serpent under't,