Hi (Eugene?) .. just a quick response, besides the structural follow up on contents which I propose to do on the page for ‘Mystery Schools tradition’ or ‘Initiation’, if you want to.
I’d like to clarify something upfront.
We are in danger here of talking across purposes, because there is a well known schism between people who talk from experience regarding initiation and the spiritual, and those who don’t.
That is not a value judgement, Rudolf Steiner also described on many occasions that even advanced Individualities, for various reasons, were not able (yet) to embrace, accept or come to spiritual science in their incarnation in the 19-20th century (examples Haeckel, Nietzsche, etc).
This pattern is still there today of course: one finds people who are in front of the gate of the spiritual but cannot accept even the existence of a spiritual reality. Others are pivoting or doubting somewhere in the greyzone, others are ignorant and just not ready for the question or consideration, whilst still others are fighting the spiritual out of their current belief system. All this is normal and follows spiritual maturity and karmic history, the population consists of different cohorts or segments at different stages of their karmic balance and development between the intellectual and consciousness soul. Faculties that are an antidote to conflict, like openness of mind, asking questions, .. also relate to this.
The sources you mention accept that things like initiation and a higher metaphysics exist (as one can hardly ignore their reality in history), but then go on and want own subject matter and provide an intellectual explanation. This to me is like spiritism in the 19th century, it sidetracks from the truth. It is not that these sources are not informed, or not good scholars, or don’t come up with certain things that may be true, but untruth is worse and more dangerous than ignorance.
No authority should be granted to people who don’t have the credentials to be able to talk about these things from the wisdom of experience. And that is a characteristic of the FMC wiki and its choice of and focus on certain sources.
There are thousands of books by respected scholars through the ages, and often people resonate with this or that stream of thought for good reasons of karmic history and spiritual maturity .. one lands where one needs to be in order to take the next step. Therefore it would not be realistic to expect all of us to speak the same language, and so we can respectfully accept and agree to disagree.
Initiation is a pathway with many stages. Seeing the spiritual in nature is one stage, experiencing the astral world is another, and the lower and higher spirit world are yet different worlds and experiences. Each world has corresponding faculties that Man can have and develop, whether astral or mental travel, clairvoyance, evocation of spirits, etc. The experience of Unity that is being talked about in the sources you mention is just one stage, and not the final one, as Man can develop capabilities beyond this (eg learn and master the language of creation). And obviously not everyone can or will develop all of what is possible. But the best way to the mystery of initiation, if you live with this question, is to pick up practice of self-initiation and commit to exercises yourself. Even the experience of vacancy of mind in the first step of Franz Bardon’s IIH will deepen your perspective more than reading any number of books (as the saying goes .. an ounce of practice is better than tons of theory).
Happy to take this further in a structured way as I offered before, and go in to the other questions you had (w/ regards to Rudolf Steiner and lesser/greater mysteries, and certain things you wrote that would be good to clarify because they are not correct, such as “For Steiner, Initiation was about achieving clairvoyant perception and establishing conscious links with the occult forces of “nature”.)
What I wrote above might require deepening and in-depth explanations for every sentence, and the site contains materials to assist in explaining for the earnest open minded student interested in learning. This would however lead us too far here.
Nevertheless, to stay on topic, the following is a first set of pages worthwhile to study as a foundation to initialize’s one’s understanding:
• Man's transformation and spiritualization, Mystery School tradition, initiation,
• Franz Bardon and initiation, IIH, initiation exercises.
• God experience, Stages of clairvoyance, Kundalini.
If you’re interested in symbols, take a look at
• Symbols, Book of Ten Pages - as related to what is on ‘Cosmic fractal’
Also relevant to our exchange and comment above: