<span>Peter's fidgeting with his pen-knife and Clarissa's use of her scissors during the conversation symbolize that they both have some aggression towards each other and their default way to converse is defensive.
</span><span>The description of Peter's thoughts suggests that he disapproves of Clarissa's lifestyle. --It is clear that Peter does not think Clarissa is doing anything worthwhile, and is judging her actions harshly compared to thinking of himself and his accomplishments very highly. </span>
I believe it could refer to the fact the joy is in fact joyful
