Final answer:
The last line of Macbeth reveals his state of mind, which is characterized by deception, inner turmoil, and a struggle between appearance and reality.
Step-by-step explanation:
The last line of Macbeth, 'False face must hide what the false heart doth know,' tells us about his state of mind. It shows that Macbeth has become deceptive and that he must mask his true intentions and emotions. This line demonstrates his inner turmoil and the conflict between appearance and reality that he faces. Macbeth's state of mind is one of guilt, fear, and the need to cover up the evil deeds he has committed.