Came across this today. I still like it.

Unanswered questions are far less dangerous than unquestioned answers.

… But as records of courts and justice are admissible, it can easily be proved that powerful and malevolent magicians once existed and were a scourge to mankind. The evidence (including confession) upon which certain women were convicted of witchcraft and executed was without a flaw; it is still unimpeachable. The judges’ decisions based on it were sound in logic and in law. Nothing in any existing court was ever more thoroughly proved than the charges of witchcraft and sorcery for which so many suffered death. If there were no witches, human testimony and human reason are alike destitute of value. — Ambrose Bierce, “The Devil’s Dictionary”