This was revolutionary stuff. Conventional wisdom was that humans were different from animals because we had language. John Lilly popularized the concept that we are not alone. We didn't need to explore outer space to find intelligent life. We weren't so different.
He was also a more scientific approach to looking at drugs as mind expanding. Programming and Metaprogramming of the Human Bio-computer  was written well before the common meme that we are computers. And his work with sensory deprivation tanks inspired the movie Altered States .
I still play the 'cogitate' tape loop from Big Sur for people even though most people don't get it.
While I never did get a chance to try a tank, Lilly showed what it was like out on the edge.