Nico Muhly’s music has been aptly compared to a six-lane highway on which all the cars are trying to switch lanes at the same time. Near the end comes the Miracle, when everything finally comes together, and you’re never sure how.

When Philadelphia Orchestra audiences hear Muhly’s new organ concerto this week, their best way into the piece — co-commissioned by Philadelphia and the Los Angeles Philharmonic — will be to monitor the musical traffic.

It was Muhly’s friend and colleague violist Nadia Sirota who recently coined the highway description. And as breezy as it sounds, the composer doesn’t argue.

“I’ll take it,” Muhly says. “But it sounds more like my life!” (More on his interior traffic later).

The fashionable, 37-year-old post-minimalist composer is currently best known for the troubled psychology he probed in his recent opera Marnie at the Metropolitan Opera. (The Philadelphia Orchestra premiered the orchestral suite from the piece this season).

In person, Muhly talks faster than anybody and looks more like a downtown club kid than the maturing composer that he is. He effortlessly inhabits seemingly disparate worlds, both in life and in music.

An openly gay man who playfully refers to himself with feminine pronouns, Muhly identifies as Anglican — Ash Wednesday loomed large on his calendar last week — and doesn’t hesitate to say, “Sacred music is so much at the heart of what I think about.”

‘Marnie’ goes to church

Titled Register (after the array of sounds summoned by the knobs on the organ), the concerto might be nicknamed “Marnie goes to church” because it inhabits the lush orchestral world of the opera (based on the novel that inspired the Alfred Hitchcock film) and can’t help having liturgical implications with the presence of the organ.

In fact, a stately pavane by British composer Orlando Gibbons (1583-1625) lies at the heart of the multilayered work, though it doesn’t come to the fore until near the end.

Having written for organ extensively in the past, Muhly thinks of the instrument as similar to an electronic sound synthesizer that makes cinematic shifts in tone and volume. “It’s baked into the history of the instrument,” he says. “I don’t do anything particularly novel in that way.”

Yet there’s never been an organ concerto like Register. It unfolds in a seamless single movement. Traffic-wise, it always knows where it’s going, even though some instruments take unforeseen alternative routes.

The Fred J. Cooper Memorial Organ at the Kimmel Center. (Jim Roese)
The Fred J. Cooper Memorial Organ at the Kimmel Center. (Jim Roese)

The limousine among them is the Kimmel Center’s Fred J. Cooper Memorial Organ, which will interact more readily with other instruments than is often heard in organ concertos.

“It’s like a candle with a swarm of insects around it,” says British organist James McVinnie, the soloist here as well as at the concerto’s world premiere last year in Los Angeles. But when the organ takes the spotlight in the big, showy cadenza, the melody is played on the organ pedals. Athletic, indeed.

‘Distinctly Nico’

“The piece is a hybrid,” says McVinnie, “between baroque efficiency and the minimalist tradition you hear from Philip Glass … very familiar but distinctly Nico as well.”

Time and again, though, Muhly’s account of writing the concerto comes down to a few basic things, and not what you’d think. With the Gibbons pavane, he’s after the “resonance” of the quotation, like what you hear from a gong, but in the seconds after it’s struck. Muhly also contemplates what is between Gibbons’ notes — “the negative spaces, weird suspensions, deliciously excruciating harmonies.”

The musical highway effect is how sacred and secular come together. Ask, for example, what the story is with those odd self-contained harp solos that pop in and out, and he compares them to the side chapels in a church. Maybe Muhly isn’t building cathedrals, but he’s thinking along those lines.

Another compass for these creative decisions was his long-standing friendship with McVinnie. “The piece is not just a playground to work out artistic fetishes,” says Muhly. “The personal element is really important.”

And that, perhaps, is one key to creative survival when this kid from an academic Vermont family suddenly found himself in the glaring, high-tension world of international orchestras and opera companies. At 22, Muhly went from the Juilliard School to being the right-hand man for Philip Glass (editor, conductor, etc.).

He worked with a few indie bands in New York and he was not yet 30 when he finished his first opera, Dark Sisters, for Opera Philadelphia. A thoughtful examination of Mormon women who lose their children in a government raid, the opera wasn’t a sensation so much as it was something that listeners took to heart. What followed was the much-darker Two Boys, about the deception of internet dating, that arrived at the Met in 2013.

A new effervescence

At times prickly, temperamental, depressed, and anxious, Muhly seemed like a changed and happier man when he returned to Philadelphia in 2015 for a new curtain raiser written for the Philadelphia Orchestra titled Mixed Messages. After the premiere, longtime Muhly watchers knew why.

“I have been, it turns out, unwell for a long time,” began an understated May 2015 posting on his blog, nicomuhly.com. “From 2009-2014, I wrote two operas, several orchestra pieces, a few film scores, tons of choral music and pile of chamber music … maybe I wasn’t feeling as great as I might.”

What followed was a harrowing saga of seeing psychotherapists because they took his insurance and being on the wrong medication while nearly working himself to death. He details public displays of behavior that left him appalled the morning after. With those issues properly addressed, the world more often sees the effervescent Muhly of his better days.

He also resolved not to read reviews. And if he did, he’d find little consensus.

Response to his work is all over the map. Thus, his definition of success is now measured by the reaction of his performers. Marnie, for example: “As long as everybody is on that train and happy to walk out on stage in whatever crazy costume … that is what’s most important to me.”

Another passenger on that train is Yannick Nézet-Séguin, who introduced the Philadelphia performances of “Liar” (From Marnie), calling Muhly a genius.

The regard is mutual. With the Marnie suite reprised by the Philadelphia Orchestra at Carnegie Hall on Friday (March 8) — and this week’s organ concerto at Verizon Hall — Muhly proclaimed, “A double dose of Yannick! What more could a girl want?”

Maybe another opera commission?

Actually, the lower-stress concerto world is fine with him: “I’d write another opera in a minute. Just not this minute.”

CLASSICAL MUSIC

Register, Concerto for Organ and Orchestra

The Philadelphia Orchestra performs Muhly’s concerto, along with Tchaikovsky’s Manfred Symphony, Thursday and Saturday, March 14 and 16, at the Kimmel Center. Tickets: $34 to $153. Information: 215-893-1999 or philorch.org.