Agnes's letter encapsulates the role she plays in David's life. Although she consistently encourages him to be a better and more mature person, she does so without infringing on his own agency. Here, she simply assures David of her confidence in him, which in turn motivates him to be the wise, self-assured, and resilient person she knows that he can be. Her remark about "turning affliction to good" is especially significant, because it speaks to one of the primary ways in which Dickens suggests people can become masters of their fate rather than victims of it; by reframing his losses as opportunities for growth, David demonstrates his purposefulness and resolve.