Beware of false knowledge; it is more dangerous than ignorance.

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

It is dangerous to know, but it is more dangerous not to know.

My ignorance wasn’t just annoying. It was dangerous.

It is worse still to be ignorant of your ignorance.

The only thing more dangerous than an idea is a belief. And by dangerous I don't mean thought-provoking. I mean: might get people killed.

The only thing more dangerous than an idea is a belief.

In the long run it is far more dangerous to adhere to illusion than to face what the actual fact is.

The most dangerous of all falsehoods is a slightly distorted truth.

Ignorance is fatal.

There is nothing more frightful than ignorance in action.

Nothing is more frightful than to see ignorance in action.

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

The greatest obstacle to discovery is not ignorance — it is the illusion of knowledge.