This is not to say that magical practitioners have always been forthcoming in their writings. Alchemists famously wrote about their practical techniques in allegorical forms that academics have spent years deciphering and also may have veiled their spiritual practices in the language of primitive chemistry. Much of this was due to ongoing persecution by the Church and this is not the sort of blind that I'm talking about. A blind in an alchemical procedure would be something like writing out an explicit procedure but giving the instruction to heat a mixture over a flame when what you're really supposed to do is freeze it. That way anyone who tried to follow the procedure would fail to produce the desired result.
Unlike veiling one's work in allegory, there is little point in promulgating such a blind. If you publish an explicit procedure there is no utility in deliberately getting it wrong. If you don't want people to know how you do your work you either shouldn't publish it or you should write about it symbolically and omit practical details. Magick was generally kept secret for much of human history rather than being published at all and the grimoires we have are likely texts that were copied from master to student for centuries. There likely were additional oral teachings that accompanied those texts, but it seems to me that this would most likely be additional material not mentioned in the text rather than something like "you need to remember that the attributions on pages 22, 34, and 57 are reversed."
The appeal of the "blind" model is that it lends a sense of historical legitimacy to original work. A lot of people still have this idea that magick was once more "pure" and worked better for the ancients, kind of like New Agers who talk about a historical Atlantis with interstellar space travel and medical technology far in advance of our own. In fact, there are various archaeological sites that may have been the inspiration for Atlantis, and while what we know about those sites tells us that they had very advanced technology for the time period in which they were inhabited, we have yet to find any ancient space cruisers, ancient circuit boards, or even a piece of ancient plastic. Any historical Atlantis was almost certainly not even an industrial age civilization, let alone the information or space age one that some imagine.
In magick innovation is often seen as suspect by people with such beliefs, but calling a new discovery the unveiling of a deliberate blind implies that the new technique is not a product of invention or original work but the rediscovery of an ancient truth. The problem here is with people who expect ancient magick to work better, not with the new techniques. If a new technique is accompanied by empirical research demonstrating its effectiveness it should be accepted and adopted as an effective new piece of technology just like any other scientific advance. But as in scientific research, the burden does fall on the experimenter to show that the new technique works better than the technique it is intended to replace. Claiming that a new technique is the correction of a blind muddles this process, and hopefully any such claim is the result of a genuine misunderstanding rather than a simple desire to avoid doing any empirical work.
So the next time you see someone talk about a marvelous ancient magical technique revealed by his or her research make sure you find out what empirical results the new technique has produced. Just because a revised model or schema sounds logical or corrects an apparent inconsistency in the existing material doesn't mean it's better. In fact, the inconsistency might have been added to the original material precisely because some magician centuries ago found that their results turned out better that way despite it.
Also try this free pdf e-books:
Max Heindel - Ancient And Modern InitiationHerbert Stanley Redgrove - Alchemy Ancient And Modern