As she’s replaced religion with science as a guiding force in her life, scientific studies have come to have a force like scripture for Gifty: she uses them to interpret and understand the world around her and how it works. But just as religion’s ability to answer big questions is limited, so too is science’s. Just because Gifty understands the power of repeating thought patterns to shape behavior and outcomes doesn’t mean she can fully apply this knowledge to Nana, since she doesn’t really know what his thought patterns were. The best she can do is guess, based on her knowledge of her brother, what he was thinking.