Act 3, Sc. 1, lines 50-55: How does Cludius's aside relate to the play's theme?

Claudius talks about how duplicity and sin takes a toll on one’s conscience and soul. One might get away with a crime but the crime and sin still exists in the perpetrator's heart. Claudius is listening to Polonius instruct his daughter on duplicity. Claudius is reminded of his own nature and sin which, despite acting like he is fine, weighs heavy on his soul.