ANNALS OF IDEAS about brainstorming and creativity. In the late nineteen-forties, Alex Osborn, a partner of the advertising agency B.B.D.O., decided to write a book in which he shared all of his creative secrets. “Your Creative Power” was filled with a variety of tricks and strategies, but Osborn’s most celebrated idea was the one discussed in Chapter 33, “How to Organize a Squad to Create Ideas.” When a group works together, he wrote, the members should engage in a “brainstorm.” The book outlined the essential rules of a successful brainstorming session. The single most important of these, Osborn said, was the absence of criticism and negative feedback. Brainstorming was an immediate hit and Osborn became a popular business guru. The underlying assumption of brainstorming is that if people are scared of saying the wrong thing, they’ll end up saying nothing at all. Typically, participants leave a brainstorming session proud of their contribution.