Brightness
How much light you bring to what you're looking at. Controls whether you see the hopeful side or the dark side of a situation.
The Grandmother's Journal Entry
Brightness controls whether someone sees the hopeful side or the dark side of what they're looking at. The granddaughter had been reading her present hardship as evidence of permanent failure. After finding her grandmother's journal entry and seeing the full life that followed that one dark moment, she adjusted how much light she was bringing to her own situation — moving from 'this is how it ends' to 'this is just one hard page.'