This intriguing book traces the issue of things we are not supposed to know as it appears in religion, science, government, and psychology. That is, the author explores forbidden knowledge from the Garden of Eden and medicine in the Middle Ages; to Galileo's world view, Darwinism, nuclear power,and cloning in science; to classified information and government secrets such as the treatment of prisoners at Abu Ghraib; to the memories we suppress as inconsistent with our self-image. The argument is that knowledge should not be forbidden unless there is a vital and compelling reason to do so.