In history you read about elves, fairies, little people, spirits. It was an accepted part of reality.
But now that’s obvious nonsense and if you see fairies then you need a doctor.
Are we insane now?
Yes I know, nutrition, literacy and the scientific enlightenment. But still.
And mouldy bread. And eyeglasses are a pretty recent invention.
If you are wearing eyeglasses then your vision has been distorted and cannot be trusted.