Don’t Think that Because I Understand, I Care.
“In that direction,” the Cat said, waving its right paw round, “lives a Hatter: and in that direction,” waving the other paw, “lives a March Hare. Visit either you like: they’re both mad.”
“But I don’t want to go among mad people,” Alice remarked.
“Oh, you can’t help that,” said the Cat: “we’re all mad here. I’m mad. You’re mad.”
“How do you know I’m mad?” said Alice.
“You must be, said the Cat, “or you wouldn’t have come here.”
The origin of the phrase “Mad as a hatter”, it’s believed, is that hatters really did go mad. The best sorts of top hats were made from beaver fur, but cheaper ones used furs such as rabbit instead.
A complicated set of processes was needed to turn the fur into a finished hat. With the cheaper sorts of fur, an early step was to brush a solution of a mercury compound—usually mercurous nitrate—on to the fur to roughen the fibres and make them mat more easily. Beaver fur had natural serrated edges that made this unnecessary, one reason why it was preferred, but the cost and scarcity of beaver meant that other furs had to be used.
Prolonged exposure to the mercury vapors caused mercury poisoning. Victims developed severe and uncontrollable muscular tremors and twitching limbs, called “hatter’s shakes”; other symptoms included distorted vision and confused speech. Advanced cases developed hallucinations and other psychotic symptoms. I’d always thought the madness came from something in the tea. Go figure.