In 1988, William Poundstone—author of numerous books, including the “Big Secrets” series and the recent corporate-brainteaser bestseller How Would You Move Mt. Fuji?—started recording what Thomas Mann called “the flattering inventions of a dream, which the waking sense proves worthless and insubstantial.” To wit: seemingly brilliant ideas that occurred to the slumbering Poundstone, which (alas) proved to have no merit whatsoever in the morning. An acclaimed web artist, Poundstone has posted these dreams on his site, williampoundstone.net. A selection follows.

10 JULY 2003

I was in heaven, and it was cheap and flimsy, like it had been built quickly with substandard materials. A lone Mini Cooper drove by. Cars were rare; most people took public transportation. I spoke with a being who may have been God. “You can’t understand our affairs,” “God” said. “To us, you’re like a microbe!” It was hilarious because I knew he was really trying to convince himself.

EARLY DECEMBER 2002

I acquired a rare promotional kit for shrunken heads. It had certificates of authenticity for the heads and a newspaper clipping about the first shipment of shrunken heads arriving at Macy’s. All of this dated to an earlier era when shrunken heads were mass-marketed to the American public. I realized that the promotional kit could be the basis for the definitive magazine article on the whole shrunken-head phenomenon.

15 JUNE 2002

I was reading about Mexican cat pornography in the New York Times. They use female cats that have just given birth, and are “bloated.” An actress uses these cats as a cushion or pillow. The action is filmed “under harsh Mexican light.”

The article reported the discovery of a cache of this Mexican cat pornography (known as “MCX” for short—as if law-enforcement officials had to deal with this so much that they couldn’t be bothered to say the whole phrase) starring the actress Kirstie Alley. The cache had been discovered in Alley’s hometown of Lynn Grove, in or near White Plains, New York.

In the next part of the dream, I was in Lynn Grove, in a small house or apartment, with Alley and an unidentified man. I was some kind of reporter. I asked the man (adopting an ironic, stagy tone), “Is there any of this stuff about? I mean, just for reference purposes!”

Alley pretended to be offended. But really, she was taking this all as a good sport. She had been young and unknown when she did the cat pornography. It was all a big joke to her now.

The room contained a large number of encyclopedia volumes, which I understood to contain the pornography. I woke before seeing any of it. On waking,...