Not many singer-songwriters have the guts to go out on the road and rock an unwieldy, if elegant, Celtic harp. Much less sing verse after verse of lyrics that take an almost archaic pleasure in language as a kind of lost kingdom: a fabulist realm where monkeys and bears are lovers, phrases like “hydrocephalitic listlessness” flow as easily as “moon” and “June,” and the natural world becomes a boundless source for star-swept illumination.

Joanna Newsom, in fact, is the only one. And she’s doing it again. In 2006, the 26-year-old performer toured with the small band behind her epic album “Ys” (pronounced “eees”; the name belongs to an ancient city of Breton myth). The recording project was incredibly complicated, involving the legendary arranger Van Dyke Parks, a 30-piece orchestra, a small ensemble of musicians from Ms. Newsom’s circle, and the famed engineer Steve Albini.

Suffused with intimate instrumental detail and surging with an emotional turbulence that welled from the unlikely source of Ms. Newsom’s soprano, “Ys” may have flummoxed some listeners who knew of the singer only from her modestly scaled 2004 debut “The Milk-Eyed Mender.” But for many it was an astonishment, something to be slowly appreciated as if a secret was being revealed.

Ms. Newsom is still engaged in that revelation, as she headlines shows tomorrow and Friday with members of the Brooklyn Philharmonic at the Brooklyn Academy of Music’s Howard Gilman Opera House. The two-hour concerts will be among several Ms. Newsom has been doing with orchestras around the country.

“I guess the desire just came from the sense that, if I make an orchestral recording, then I ought to try to do some orchestral shows,” Ms. Newsom said via email, her preferred mode of communicating with interviewers. When she last visited New York to play songs from “Ys,” she brought a small combo of musicians who evoked the music’s rustic sublimity with a handful of instruments, gamely capturing the spirit — if not the sweep — of Mr. Parks’s arrangements.

As it turned out, that will only ever truly exist on record.

“The score we’re using is a modified version of Van Dyke’s score,” Ms. Newsom said. “Ryan Francesconi, who also plays tambura in my band, had to tweak the scores to a point where they made sense in the context of a live performance. For reasons that are too complicated to go into here, the original scores were much better suited to a studio recording (having been written to match up perfectly with the particular harp and vocal takes over which they were overdubbed) than to a live performance.”

Though she lamented that some of the orchestral musicians with whom she has performed have approached the occasion as just another gig, she was especially gratified by her recent experience in Australia. “Sydney was amazing,” she said. “The Sydney Symphony. They got into it. A lot of other shows have felt great in that way, too, like the musicians are really listening and responding in a musically sensitive way.”

On a good night, the tour seizes the chance to realize “Ys” the way it really ought to be heard.

“If we have enough rehearsal time, and there’s enough communication that happens between me and the conductor and Ryan and the orchestra, the thing should end up sounding quite a bit better than on the record,” Ms. Newsom said. “There’s a level of syncing up and feeling like a single musical organism that’s real difficult to achieve on a recording of that scale, with so many overdubs. I think that particular phenomenon is just a (best-case-scenario) possibility of live performance.” Ms. Newsom’s second orchestral performance, which was staged in Atlanta in November, left her feeling ecstatic, which in turn left all those around her ecstatic.

“I remember she came off the stage at the end of the concert and she was so overwhelmed,” Tanner Smith, who promoted the event with the Atlanta Symphony Orchestra, said. The singer wondered if she ought to go back out and do an encore, and Mr. Smith gave her a nudge. “She was blown away.”

The five songs on “Ys,” which Ms. Newsom will perform at BAM in addition to other material, are written in a proudly verbose style that feels playfully antiquated and deeply allegorical. Her harp playing, which has become virtuosic after nearly 18 years, steers sharply away from anything new-agey, with its rigorous, cyclical lines rooted in West African kora playing. And for all the unusual elements that underpin her music, the way Ms. Newsom sings, often with trembling, full-throated passion, suggests immediate and personal inspirations.

“It’s hugely autobiographical but, then, it’s a fictional narrative,” Ms. Newsom told me in a previous conversation, not long after the album’s release. “It was an effort on my part to organize and score and make some sense of and articulate my reaction to a year of my life that was a very hard year. I mean, obviously, there are overt enough references to mortality on the record, it’s clear that’s a huge thing. There was a lot of death that was rough for me, but also other kinds of death. And some really, really good things that happened, too.

“One thing that was really important to me, and I really made sure this was the case — every lyrical line means something really, really specific to me,” she said. “There’s no arbitrariness. No saying something because it sounds good. Every single line is an effort to be completely truthful and to say something in a certain way. At the same time, it’s not hugely important to me that anyone else ‘get’ the story.”

The songs retain the same meaning for her now as then. And for all the ways in which they make the listener want to contrive a way to describe their effect — sort of Chaucer meets 1972 Bruce Springsteen at an early-music consort? hmmm — Ms. Newsom suggested only that she had taken a lot away from reading William Faulkner’s “The Sound and the Fury.”

But, she said, “Only in that there’s one story that book aspires to tell, and the different angles from which the story is told are so incredibly different. The first three sections involve people doggedly running in circles around particular obsessions. There are psychological hiccups they can’t free themselves from, but the loops and the circles sort of take on this particular shape, and all of these characters together, their different obsessive running — the shape that those things form in relief is sort of the story, you know?”

Ms. Newsom performs tomorrow and Friday at the Brooklyn Academy of Music’s Howard Gilman Opera House (30 Lafayette Ave., between Ashland Place and St. Felix Street, Brooklyn, 718-636-4100).