I understand what you are stating and asking. While you are well-versed in philosophy and philosophical terms and concepts, I am only on the periphery. I say this because it seems to me that words are getting in the way. The ineffable cannot be explained or described, as we've noted.

Yes to your statement that reading informs you, and information can spark insights too. I use the word "realization," but it may be inadequate. My use of the term is to suggest something that is beyond thought, though to explain it requires thought. And it is clear that people incorporate what they know — what they have read, heard, or believe, to suggest a mystical experience when it is no more than a concept that makes them feel good or important. We see a lot of this in religion, historically, and in the New Age movement wherein filling oneself with positive thoughts brings about an elation that is confused with some notion of spiritual enlightenment, superiority, great wisdom, or ascension.

You wrote, "If we call it an impression, though, the question is whether first impressions are always what they seem." I agree with this statement as well, including for reasons I stated in the above paragraph.

At this point I must ask you if you have ever had thought completely turn off, as if a switch had been thrown and all thoughts have ceased. When this occurs there are no impressions, insights, memories, or mentation. There is only clarity. In this clarity the self is not, and there is no suffering; and there is no wonder, awe, or imagery. There is clarity alone. Have you had this? Many people have experienced this clarity by accident, as have I. But this state, so to speak, can also be realized, as have I, by persistent enquiry into the self so that it gives way to both everything and nothing at the same time. Is this all in the mind or head? Perhaps, because this is the way we come to know anything, including what is occurring to us, but it just doesn't matter, because there is no interest to impress anyone or prove one's point. There is only the realization of what one is devoid of thought.

Now, you are trying to understand this from a certain point of view, which includes all of your education and personal experience, all of which are valuable to your work and to life in the world. But when it comes to this clarity the same information/education/knowledge becomes and obstacle, a hindrance.

I offer no argument with what you are saying about thoughts or impressions at all. To explain something takes words, and words are inadequate when it comes to knowing or experiencing this clarity of what one is (and therefore what reality or life is). So it seems that we are running parallel to one another. I would not be the first to say that there is no way into this understanding that includes all the regular tools of thought, wisdom, effort, concentration, or intelligence.

With the clarity of which I speak comes an engagement with everything, the totality of consciousness. It is a full realization that there is bad, good, and everything in between. In the clarity is a knowingness (but not the same knowingness that is actually a belief in what has been learned) that nothing exists in isolation and that all is a movement, yet it is the self that parses or fragments this movement so that it can deal with it. Due to the processes of the conditioned brain or mind we come to believe that the movement is really fragmented, and in doing so we believe that we are separated from all else by a body and all the identities, beliefs, and associations that we have formed. The fragmentation is absolutely necessary to navigate our world, interact, eat, drink, and be merry. No doubt. But the fragmentation creates a delusion about what we really are. It's really a simple thing.

And so I am speaking of this clarity and knowing what I am, but it seems you are trying to quantify or qualify the process, cause, and effect for the purpose of differentiating the mystical experience from thought and delusional thinking. I can appreciate this, but it really has nothing to do with the clarity of realizing what one is and how this is a representation of how everything is — as well as how everything emanates from the void or nothingness; and how everything is, essentially or fundamentally, the void itself.