During the darkest time in German history, incited mobs threw stones into the windows of innocent shop owners and women and children were cruelly humiliated.

A young German Lutheran pastor Dietrich Bonhoeffer began to publicly speak against the atrocities. After years of trying to change people's minds, Bonhoeffer was arrested and sent to prison. Here, Bonhoeffer reflected on how the poets and thinkers of his own country had turned into a collective of cowards, crooks and criminals. He finally concluded that the root of the problem was not malice, but stupidity.

Bonhoeffer argued in his famous letters from prison that stupidity is more dangerous than malice because one may protest against evil, and it can be exposed and prevented by the use of force. But we are defenceless against stupidity. Protests or force can do nothing, and reasons fall on deaf ears. Facts that do not fit a stupid person's prejudgment are ignored or pushed aside as inconsequential or incidental. 

However, being easily irritated, this stupid person becomes dangerous by attacking. Therefore, great caution is needed when dealing with a stupid person.