“[Bill] Gates is a doodler, and he’s not alone. Lyndon Johnson doodled. Ralph Waldo Emerson doodled. Ronald Reagan drew pictures of cowboys, horses and hearts crossed with arrows. Most of us doodle at one point or another. But why? To understand where the compulsion to doodle comes from, the first thing you need to do is look more closely at what happens to the brain when it becomes bored.”