The "I don't want to break the machine" part from the book was mainly about alcohol, and only secondarily about LSD: > I started to walk into the bar, and I su

The "I don't want to break the machine" part from the book was mainly about alcohol, and only secondarily about LSD: > I started to walk into the bar, and I suddenly thought to myself, "Wait a minute! It's the middle of the afternoon. There's nobody here. There's no social reason to drink. Why do you have such a terribly strong feeling that you have to have a drink?" ­­ and I got scared. > I never drank ever again, since then. I suppose I really wasn't in any danger, because I found it very easy to stop. But that strong feeling that I didn't understand frightened me. You see, I get such fun out of thinking that I don't want to destroy this most pleasant machine that makes life such a big kick. It's the same reason that, later on, I was reluctant to try experiments with LSD in spite of my curiosity about hallucinations. Also, according to this passage, Feynman's experiments with LSD/hallucinations came after (and despite) this decision, and they are described extensively in the book. I don't remember a mention of Timothy Leary in the book (it mentions John Lilly; maybe you've mixed up the two), and I also don't remember the part about him giving a talk about a problem he thought he had solved.