Smells can be powerful forces, triggering memories and emotions. But for millions of people who caught COVID-19, they’ve been lost — at least temporarily. The reason for that is unclear. Smell itself is largely unknown, even for the world’s master perfumers. Writer Scott Sayare dives into the mystery for the latest issue of Harper’s Magazine. He’s joined by Saskia Wilson-Brown, the director of the Institute for Art and Olfaction.