In a nutshell, for Chiico to write this beautiful masterpiece is because she was asking for forgiveness from her boyfriend/lover. As you all know they are two sides of the same coin and two sides of a story. Grace is a gift we don't deserve, while mercy is not getting the punishment we deserve. Mercy, on the other hand, is the compassion and kindness shown to someone whom it is in one's power to punish or harm. It is an act meant to relieve someone of their suffering.