Throughout history, dissidents have often come under attack. They have encountered censorship, harassment, slander, dismissal, banishment, even prison, torture and execution. In liberal democracies today, intellectual freedom is celebrated. Yet it remains dangerous to disagree with conventional wisdom. Inside corporations and government departments, most employees know it is not wise to criticise official policies or the boss - at least not openly. Those who speak out are often victimised. Suppression of dissent is commonplace. Yet this suppression receives little attention.