OK, that LSD (or more properly N-propionyl-LSD) was stronger stuff than I anticipated, though I felt like I had to work harder for a breakthrough than happens with psilocin, which gives me really vibrant, visual, fluid experiences.

A voice in my head I haven't spoken to in a while was an important part of this experience, an entity I dubbed "The Engineer" back when I first encountered him (pretty definitely a "him" in my head) some time last year. (Here's an old account of that meeting, and how it came about: https://monophylos.livejournal.com/4523.html) The 9th Symphony seemed to elicit him.