"The ancient Greeks paraded enormous sculptural replicas in annual celebration of the penis; Freud theorized that women suffered penis envy. An undeniable, global symbol of power and virility since the beginning of humankind, the penis has been much discussed, gestured towards, and depicted, yet seldom understood outside folklore and popular culture's uneasy mix of self-deprecation and aggrandizement. Despite the penis's central role in human life...