Nothing is more frightful than to see ignorance in action.

There is nothing more horrifying than stupidity in action.

There is nothing so dangerous as an ignorant and frightened man.

Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.

Nothing in all the world is more dangerous than sincere ignorance and conscientious stupidity.

Ignorance is fatal.

Es ist nichts schrecklicher als eine tätige Unwissenheit.

It is worse still to be ignorant of your ignorance.

Ignorance is a dreadful thing and has caused no end of damage to the human race.

Ignorance is the parent of fear.

The one thing that is more dangerous than true ignorance is the illusion of understanding.

There is no terror equal that of the ignorant in a strange place.

Ignorance is the parent of fear

There is nothing worse than aggressive stupidity.