Didion isn't describing writing as a tool for *expressing* pre-formed thoughts—she's saying the thinking itself doesn't exist until the words arrive on the page. Most people assume they must understand something before they can write about it; she reverses that entirely. It's why a scientist staring at confusing lab results, or a parent trying to make sense of a child's illness, often finds clarity only while writing an email to a friend—the act of arranging words forces the mind to organize what it couldn't before. Her insistence on "what I see" matters too: she's not writing about abstractions, but always about the specific, visible world, which is the only honest ground from which understanding can grow.