I just love returning to topics yonks after they seem to have ended!
I always thought the Masked Magician thing was a fairly recent event but was totally wrong. We know that Reginald Scott published 'The Discoverie of Witchcraft' in 1582 but that wasn't so much a secrets revealed but more to try and show that burning folks as witches etc wasn't really nice as there's usually a better explanation than witchcraft - in this case sheer skill.
Another book called Modern Magic was written by an Oxford educated London barrister called Angelo Lewis, but who used the pen name of Professor Hoffman, because (get this!) he was 'disturbed at the snail-like progress of his beloved magic, as well as a certain sameness in the performances he witnessed'. He decided to stir things up a bit by exposing the secrets in the expectation that the professionals would then have to work a bit harder and develop new stuff. This was in the early 1900's and it sounds very familiar, doesn't it!
Incidentally, the nett result of the Prof's revelations was a kick up the rear for the professionals but also a boom in interest in magic from amateurs (!) and a brand new generation of lovers of magic. Most of The Prof's secrets are no longer used so his idea worked. If only Fox TV had the same good intentions!
(You can tell I've been reading my Christmas prezzie books, can't you?!)