I used to feel as if I had "a special connection to the true universe," when I was under the influence.
I decided, one time, to have a notebook on hand, and write down these "truths and revelations," as they came to me.
After coming down, I read it.
It was insane gibberish. Absolute drivel.
I never thought that I had a "special connection," after that.
I have since learned about schizophrenia/schizoaffective (from having a family member suffer from it), and it sounds almost exactly what they went through.
The thing that I remember, was that I was absolutely certain of these “revelations.” There was no doubt, whatsoever, despite the almost complete absence of any supporting evidence.
Reading it over once fully lucid? It's gibberish.
It's something I experienced as well, this sense of profound realisation of something important, life-changing maybe. And then the thought evaporates and (as you discovered) never really made sense anyway.
I think it's this that led people in the 60s to say things like how it was going to be a revolution, to change the world! And then they started communes and quickly realised that people are still people...