Ten years ago, the editor of a leading magazine invited me to lunch. I had been one of his contributors, but we had never met. He broke the ice by asking, "What is your hobby, Mr. Osborn?" "Imagination," I replied. He paused, then wrote on the back of an envelope, "MY HOBBY IS IMAGINATION." "Mr. Osborn," he said, "you must do a book on that. It's a job that has been waiting to be done all these years. There is no subject of greater importance. You must give it the time and energy and thoroughness it deserves." That remark started this book. Although I earned my master's degree in practical psychology and have devoted most of my life to the psychology of advertising, I cannot claim to be a psychologist. Nor have I tried to write as a psychologist. I have felt free to take figurative liberties with academic concepts. For instance, I realize that imagination is an integral part of man's mind-body function; and yet, for the sake of clarity and readability, I refer to imagination as if it were an entity of itself. My frequent use of the term "brainstorm" may bother the reader at first. Although Chapter 33 will fully explain, an inkling of its meaning may be helpful here: "Brainstorm" is used mainly to label the kind of conference where a few people sit down together for an hour or so solely to use their creative imaginations-solely to suggest ideas on a specific subject, right then and there. During the past ten years, in quest of material and insight, I have interviewed hundreds of people and have read hundreds of books, speeches and articles. I am indebted to all who talked with me and to all whose writings I read. Many of their names will be found in the index.