Recently the topic of the Z-2 Formula for Invisibility came up on Pat Zalewski's yahoo group. It appears that many people have been assuming this ceremony referred to actual, literal invisibility. I was under the illusion for a long time that we were not living in a fantasy novel, but perhaps I've been deluding myself (it wouldn't be the first time).
Pat mentioned that Regardie, Crowley and many others took this idea of invisibility quite seriously and literally, but I've always sided with the "people won't notice you as much" argument than actually disappearing into thin air. It surprises me a little that people who are otherwise intelligent and advanced in their magicial and spiritual training can be such literalists about any aspect of magic, especially something as fantastical as invisibility. I'm sure I'm not the only one to think that.
One thing of interest that came out of that discussion was something Alex Sumner posted:
"The Neophyte Ritual - and the Z2 formulae - is all about moving from Darkness into Light. So the 0=0 ceremony is bringing the candidate from darkness to light; Evocation is about bringing a spirit from being unmanifest (darkness) to manifest (light); talismans are about transforming an inanimate piece of cardboard (=darkness) into a magical object (=light); Spiritual Development is
about bringing the spiritual nature of the Adept from darkness to light; etc etc etc.
All of the Z2 rituals are themed about this "from darkness into light" trope - with one exception: Invisibility. Alone of all the Z2 formulae it is the Reverse: going from Light into Darkness."
Alex makes a very valid point that the Invisibility formula uses the reverse of the normal approach. I'm not entirely sure this renders it invalid, ineffective, or completely at odds with the rest of the material, as the theme of going from Light into Darkness is an important thing to explore in its own right and is something we experience on a daily and yearly basis. It does, however, raise a number of questions about its inclusion with the other formulae and if we can discover other "reverse" formulae within the system we are using.