They’d told us we were going on two bands after the Grateful Dead. He goes, “Well man, you better get comfortable because apparently, we’re not going on until one o’clock in the morning. It’s a mess here. And by the way, would you like to take some of this?” It was mescaline. And I was like, “Let’s see, it’s 12:30 in the afternoon. By two o’clock in the morning, I’ll be all right.” I used to take LSD and mescaline a lot, so I knew the timing. After eight or 10 hours, you’re into what we call the amoeba state. Your thoughts become very galactic and universal and microscoped .

Two hours after I took it, there was a face in my face that said, “You need to go on right now, otherwise you’re not going to play.” By this time I was really, really on it, you know? I just held on to my faith, and what my mom taught me. I asked, over and over, “Just help me stay in tune and on time.”

[See all of our coverage of Woodstock at 50.]

I assume that in 1969, Jerry Garcia’s mescaline was pretty potent.

Oh, it was. I’d been dosed by them a year before. It took me two to three days to coordinate after that one. I’d been baptized into consciousness expanding, I’ll call it, so that didn’t scare me.

We knew already they had a reputation for dosing other bands and since we were opening for them in Las Vegas, I made sure to carefully wash this Coca-Cola can I was going to drink. But what I didn’t know is, they knew how to put a syringe in the soda can. So we played our set and left, and on the way from the airport to the plane, the hall kept getting longer and longer. The colors in the carpet and in the wall started oozing like lava. I said, “Uh oh, they got me.” When I sat down on the plane, I looked out the window as we were taking off, and the Vegas lights looked like Aztec hieroglyphics. [Laughs] I said, “This is going to be intense.”

When you were onstage at Woodstock, were you hallucinating?

Oh totally. You can tell by my body language. I’m wrestling with the guitar — not wrestling in conflict, but like a surfer, wrestling to maintain and sustain a balance. That’s the key to everything in life. Whether you’re straight or on mescaline, maintain your composure and your balance.