What Robert Cialdini teaches about influence and persuasion in his book, Influence: The Psychology of Persuasion. — The most powerful book on persuasion is Robert Cialdini’s book, The Psychology of Persuasion. Cialdini outlines the 6 principles of persuasion that influence people. His research helps those in copywriting, marketing, and sales. If you want to master these topics, it’s paramount that you read this book.