“LSD, LSD,” he repeated. “It’s colorless, odorless, tasteless. One ounce contains 300,000 full doses. A pound or so in the water supply and—Oh, my God! Those magazine articles gave someone the idea!”

The three of us stood there drinking our soda and looking at the people screaming, the people chuckling, the people doing all kinds of crazy things. There were mobs now heading east and yelling, “Everybody to Fifth Avenue. Everybody to Fifth Avenue for the big parade!” It was like a kind of magic had spread the word, as if the whole population of Manhattan had gotten the same idea at the same time.

I didn’t want to argue with a professional man, you know, but I’d also read a lot of those magazine articles on LSD. I said I hadn’t read about people doing some of the things I’d seen that day. I mean, I said, take those crowds chanting like that?

Dr. Scannell said that was because of the cumulative feedback effect. The what? I said. So he explained how people had this stuff inside them, making them wide open psychologically to begin with, and all around them the air was full of other LSD reactions, going back and forth, building up and up. That was the cumulative feedback effect.

Then he talked about drug purity and drug dosage—how in this situation there was no control over how much anyone got. “Worst of all,” he said, “there’s been no psychological preparation. Under the circumstances, anything could happen.” He stared up and down the street at the crowds going chant-chant-chant, and he shivered.

They decided to get some packaged food and drink, then go back to their hotel room and hole up until it was all over. They invited me along, but, I don’t know, by this time I was too interested to go into hiding; I wanted to see the thing through to the end. And I was too scared of fires to go and sit in a fourteenth-floor hotel room.