Some nights, when the sky is clear over his house in Provence, Eric Idle gazes at a star called Betelgeuse and contemplates its demise. “It’s this big red giant star you can see,” Idle, a founding member of Monty Python, said last week. “It can go supernova any day.” Granted, Betelgeuse (Orion’s right shoulder) is more than six hundred light-years from Earth, and “any day” could be ten thousand years in the future. But it was enough to put Idle in a doomsaying mood. “A meteorite might do to us what it did to the dinosaurs,” he added. “Any day.”

When the apocalypse comes, it seems likely that Idle will respond with a little whistle and a verse of “Always Look on the Bright Side of Life,” the anthem he wrote, in 1978, for “Life of Brian,” the Python parody of the New Testament. In the movie, Idle sings it while being crucified alongside the title character, an unwitting rival of Jesus Christ. According to one study, it is the most requested song at British funerals, edging out “My Way.”

This week, Idle will reprise the song at Carnegie Hall, as the closing number of “Not the Messiah (He’s a Very Naughty Boy),” an oratorio based on “Life of Brian,” which Idle wrote with the composer John Du Prez. The piece—Idle’s follow-up to “Spamalot,” the Broadway musical “lovingly ripped off” from “Monty Python and the Holy Grail”—débuted with the Toronto Symphony Orchestra, in 2007. For its New York première, “I was hoping I could be ill and Marty Short would do it,” Idle said, over lunch in midtown. “But it needs an idiot. And an orchestra.”

In his Python days, Idle excelled at idiots, especially the officious kind. “Life of Brian” was “my fault,” he admitted. “We were here opening ‘Holy Grail,’ and a journalist said, ‘What’s your next film?’ And I said, ‘Jesus Christ: Lust for Glory.’ ” After concluding that “you can’t send up Christ,” he went on, the Pythons invented Brian Cohen, a Judean nincompoop mistaken for the Messiah. Days before filming began, in Tunisia, the producing company, EMI, panicked and dropped the project. Salvation came in the form of George Harrison. He and Idle had met at a screening of “Holy Grail” in Los Angeles, where Harrison told him, “Let’s go and have a reefer in the control booth.” They wound up talking for two days. “We were sort of the same thing in our groups—the free-floating radical,” Idle said. Harrison mortgaged his house to raise the funds for “Life of Brian.” In return, he got a cameo as the guy who administers use of the Mount.

The movie caused a stir when it was released. “The night before it opened in New York, a thousand rabbis came to protest it,” Idle recalled. “In Sweden, they sold it as ‘the film banned in Norway.’ ” Time has a way of turning heresies into sacred cows, which is probably why “Not the Messiah” has evaded “The Death of Klinghoffer”-style street protests. “Because we’re in white tie and tails and it’s an oratorio, it’s not perceived to be offensive at all,” its author said.

Another glass of wine came. Idle had arrived in New York two days earlier; Tuesday was supposed to have been lunch with Mike Nichols. Idle lives in L.A. most of the time, but, at seventy-one, he does not seek out movie roles. He would like to spend his comedy-legend years, he said, exploring the meaning and the origin of the universe. When he’s in London, he usually sees Brian Cox, a particle physicist at the University of Manchester. “Brian and I meet over bottles of Ruinart at a Chinese restaurant,” Idle said. “They throw us out at one-thirty in the morning, and we’re still talking about inflation theory.”

In July, the five surviving Pythons reunited in London, at the O2 Arena, for their first show together in thirty-four years. (Graham Chapman, who played Brian in the movie, died in 1989.) The reason was money: they’d been sued by a producer of “Holy Grail,” who claimed that he was owed royalties from “Spamalot.” “It was a very nice way to say goodbye,” Idle said, dismissing any chance of a tour. Not long ago, at Billy Connolly’s house in Scotland, Prince Charles gave him another offer he could refuse. “He said, ‘Would you be my jester?’ ” Idle recalled. “I said, ‘Why would I want a fucking shit job like that?’ ” ♦