The idea of creative collaboration is a relatively new one. For centuries, science and culture focused on the self self-expression, self-realization. But two is the magic number. In this hour of To the Best of Our Knowledge, we'll explore creative partnerships. Joshua Wolf Shenk talks about two of the most influential partners of all time John Lennon and Paul McCartney. And singer/songwriter Ben Folds on his collaboration with novelist Nick Hornby.