The pair is a precious unit — private, generative, even holy. We can explore a couple’s inner workings if we have an invitation to do so. Otherwise, we must use any available external means: letters in archives, revealing anecdotes, loose-lipped quips in interviews. In order to understand creativity, we must learn from couples, Joshua Wolf Shenk argues in his new book, “Powers of Two.”

Joshua Wolf Shenk doesn't believe in the myth of the lone genius. "What has one person ever done alone?" he asks NPR's Robert Siegel. "We think of Martin Luther King and Sigmund Freud and Warren Buffett and Steve Jobs as these great solo creators, but in fact, if you look into the details of their life, they are enmeshed in relationships all the way through."