Lemonick’s The Perpetual Now tells the story of a famous artist—Lonni Sue Johnson, whose work you’ve seen in the New Yorker—whose hippocampi were destroyed by meningitis. Unable to convert new experience into long-term memory, Johnson—like the famous H. M. before her—lives always in the present. Lemonick tells her story, and the truths about memory that researchers have gleaned from her experience.