“Having a memory that is too accurate is not always good” [from an evolutionary standpoint] . . .
Put another way, memory and imagination are two sides of the same coin. Like memory, imagination allows you to put yourself in a time and place other than the one we actually occupy. This isn’t just a clever analogy: In recent neuroimaging studies, Harvard psychologist Daniel Schacter has shown that remembering and imagining mobilize many of the same brain circuits. “When people are instructed to imagine events that might happen in their personal future and then to remember actual events in the past, we find extensive and very striking overlap in areas of brain activation,” he says. Other researchers have found that people with severe amnesia lose their ability to imagine. Without memory, they can barely picture the future at all.