You find yourself in a city you hadn’t visited in years, walking along a street you had once strolled down with your fingers interlacing a long-ago lover’s, someone you then cherished as the most extraordinary person in the world, who is now married in Jersey with two chubby bulldogs. You find yourself shocked by how an experience of such vivid verisimilitude can be fossilized into a mere memory buried in the strata of what feels like a wholly different person, living a wholly different life — it was you who then lived it, and you who now remembers it, and yet the two yous have almost nothing in common. They inhabit different geographical and social loci, lead different lives, love different loves, dream different dreams. Hardly a habit unites them. Even most of the cells in the body striding down that street are different. 

What, then, makes you you? And what is inside that cocoon of certitudes we call a self?