The version of Cialdini’s ‘Influence’ I’ve read a dozen times over has a sixth principle; scarcity. This one is very important. Perhaps the version you’ve read doesn’t have this one included for some reason. For anyone reading this who wishes to read Influence by Robert Cialdini, please ensure the copy you get has the sixth principle (scarcity) included. Scarcity defines value and Cialdini explains it beautifully — it honestly changed the way I look at the world.