“Power corrupts” is an ancient theme, but it is sometimes forgotten that the maxim applies not just to powerful politicians but is also writ small in a thousand other situations. For anyone with power, the potential is there. In what has come to be called the Stanford Prison Experiment, researchers at Stanford University put this to the test by running an experiment in 1971 in which students role-played prisoners and guards. The guards gradually took their authority more seriously, so much so that the experiment was canceled after six days, when student “guards” turn unexpectedly abusive. The Stanford Prison Experiment inspired the 2001 German film Das Experiment.