In years to come, those who’d been in the room would sometimes make reference to that meeting, understanding that my answer to Michelle’s question had been an impromptu articulation of a shared faith, the thing that had launched us all on what would be a long, rough, and improbable journey. They would remember it when they saw a little boy touch my hair in the Oval Office, or when a teacher reported that the kids in her inner-city class had started studying harder after I was elected.