Some time in 1976, I went into this very hip bookstore in downtown Binghamton, New York where I lived and came across two books whose covers screamed for my attention with their flaming psychedelic designs. I picked one of them up and read the blurb on the back cover. It spoke of psychedelic supermen, conspiracies and a yellow submarine. Reading bits of random pages I knew right then and there that I'd stumbled upon my Rosetta Stone -- an alternative world similar to my own that not only acknowledged the sorts of thoughts and fantasies and cultural and political references that I shared with my "out there" friends, but that did so with language that seemed like it had been plugged into the same sort of excessively electrified everything-at-once brain-sockets that our brains were sometimes plugged into. I fished the rumpled scraps of welfare-provided legal tender out of my pocket and bought both immediately.
Illuminatus! was unusual in its time because, in some ways, there seemed to be a sort of unspoken embargo against any novelist who wanted to be considered intellectually credible writing something this directly tied in to hardcore psychedelic freak culture.