He then leaped from his seat, seeking a piece of paper from the shop’s employees. On the scrap, he began to diagram some of the modernist composer Edgard Varèse’s ideas about flipping musical intervals — an approach he also describes toward the end of “Easily Slip” — and showed how he was building on Varèse’s example in “The Other One.”

After Threadgill filled up the paper with sequences of intervals and melodic phrases — the latter built from a pattern, like Morse Code, of long and short phrases — he moved to toss his notes in the trash.

I stopped him. Preserving Threadgill’s working methods is no small matter. Throughout “Easily Slip,” there are tantalizing references to recordings of vintage orchestral performances that have yet to be made available to the public. Some important collaborations, such as concerts with Cecil Taylor, ‌have not been preserved on fixed media at all.

Threadgill is thinking about fixing some of these problems. One orchestral recording in his possession may eventually see the light of day on a website, currently under construction, called Baker’s Dozen, a portal that he also plans to offer to other artists who have valuable unreleased tapes in their possession. (He mentioned the pioneering Minimalist Terry Riley as someone who might wind up providing material for the site.)

“The Other One” is a majestic addition to Threadgill’s discography, but its film version deserves a wider airing, too. It captures his sense of humor, which tended to emerge during this show whenever he was discussing photographs that he took of possessions abandoned in New York City streets early in the pandemic. He is currently sending the documentary to various festivals, he said, “to see what kind of credits we can pick up.”

Other projects in the works, as ever, seem bound to have an unconventional slant. Threadgill said that he has been impressed by the strides that collaborators and acquaintances like Anthony Davis and Terence Blanchard have had in mainstream opera, a world he says isn’t really for him.

Instead, Threadgill is planning what he called a “corrupted oratorio,” featuring two choirs: “a traditional choir and a gospel choir,” plus piano and organ, and other instruments as it develops. “I don’t like preconceived forms, you know?” he said. “I like to create new forms.”