Hi Anne,
Thanks for the comments on my new website, even though it is not yet
finished!
The bit came about by man's desire to control the horse. The first
attempt was to put a ring through the horse's nose. The septum would
tear and scar, and eventually, the control aspect became a little
less effective. People tried to find another sensitive place and so
devised the metal in the mouth.
This worked well for humans. Out of sight, out of mind was
convenient. The damage to the horse is not as visually evident. Even
today, people who 'love' their horse tend to not see the look on the
horse's face, the eyes popping out or grimaces due to pain from the
bit.
The mouth and tongue is mucous membrane. Getting 'use' to pain does
not apply here.
The founders of the original haute ecole in France were the most
humane at the time, but still used the bit. Initiates to the school
were made to wear a bridle (made for a human head) with a bit.
Another student of the school would work the reins. No one would
forget the pain induced by the bit felt first-hand and that was their
lesson in regards to respecting the horse with one.
The DVD mentioned previously covers the effects of the bit in more
detail. I have a free sample download of an extract of the film
(although the bit section is not specifically covered in this one)
You can view it by clicking here (or copy/paste the address):
http://www.haute-ecole.ru/images/he/perst.html
Michael