I've read it, and it changed the way I thought about the world., gave me respect for the scientific mode of enquiry. Also read JLS many years ago and remember being hugely inspired by it at the time - though I was 21. another was the Prophet by Kahlil Gibran, another of those 60s books sneered at these days but which contains an awful lot of wisdom if we weren't so cynical.
One leftfield book that inspired me a lot was The Function of the Orgasm by Willhelm Reich. Reich was a visionary who went a bit off the rails and whose reputation has never been redeemed as a result. I never knew until recently that Cloudbusting by Kate Bush was a depiction of the moment (from Reich's son's autobiography) when he was arrested by the CIA (never to be heard of again).
Other key (neglected) works for me would be L'homme Revolte (The Rebel) by Camus, the poetry of Robinson Jeffers, and Henry Miller's entire oeuvre