AJ remembers when she first realized that her memory was not the same as everyone else's. She was in the seventh grade, studying for finals. "I was not happy because I hated school," she says. Her mother was helping her with her homework, but her mind had wandered elsewhere. "I started thinking about the year before, when I was in sixth grade and how I loved sixth grade. But then I started realizing that I was remembering the exact date, exactly what I was doing a year ago that day." At first she didn't think much of it. But a few weeks later, playing with a friend, she remembered that they had also spent the day together exactly one year earlier.

"Each year has a certain feeling, and then each time of year has a certain feeling. The spring of 1981 feels completely different from the winter of 1981," she says. Dates for AJ are like the petite madeleine cake that sent Marcel Proust's mind hurtling back in time in Remembrance of Things Past. Their mere mention starts her reminiscing involuntarily. "You know when you smell something, it brings you back? I'm like ten levels deeper and more intense than that."

"My brother used to say, 'Oh, she's the Rain Man.' And I was like, 'No I'm not!' But I thought, what if I really. . . . Am I? Is there something wrong with me?" At one point AJ considered setting up shop on the nearby boardwalk as the Human Calendar and charging people five bucks to let them try to stump her with dates. She decided against it. "I don't want to be a sideshow."

It would seem as though having a memory like AJ's would make life qualitatively different—and better. Our culture inundates us with new information, yet so little of it is captured and cataloged in a way that it can be retrieved later. What would it mean to have all that otherwise lost knowledge at our fingertips? Would it make us more persuasive, more confident? Would it make us, in some fundamental sense, smarter? To the extent that experience is the sum of our memories and wisdom the sum of experience, having a better memory would mean knowing not only more about the world, but also more about oneself. How many worthwhile ideas have gone unthought and connections unmade because of our memory's shortcomings?