If music is a time machine, able to transport listeners to different places and eras as well as deep into memories, then Joanna Newsom steers Divers as deftly as Jules Verne.

She flits to and from 18th century chamber music, 19th century American folk music, '70s singer/songwriter pop, and other sounds and eras with the lightness of a bird, one of the main motifs of her fourth full-length.

Her on-the-wing approach is a perfect fit for Divers' themes: Newsom explores "the question of what's available to us as part of the human experience that isn't subject to the sovereignty of time," as she described it in a Rolling Stone interview.

It's a huge subject, and even though she worked with several different arrangers -- including Dirty Projectors' David Longstreth and Nico Muhly -- she crystallizes Have One on Me's triple-album ambition into 11 urgent songs that still allow her plenty of variety.

"Leaving the City," with its linear beat and electric guitar, is the closest she's come to an actual rock song; "You Will Not Take My Heart Alive" could pass for medieval music, despite its mention of "capillaries glowing with cars." While Divers is musically dense, it may be even more packed with ideas and vivid imagery; its lyrics sheet reads like a libretto (and is a necessary reference while listening).

The bird calls that bookend the album -- and the way its final word ("trans-") flows into its first ("sending") -- hint at the album's looping, eternal yet fleeting nature, while "Anecdotes" introduces how each track feels like a microcosm (or parallel universe) dealing with war, love, and loss in slightly different ways.

"Waltz of the 101st Lightborne," in which time-traveling soldiers end up fighting their own ghosts, highlights Divers' sci-fi undercurrent, which is all the more intriguing paired with its largely acoustic sounds.

Newsom combines these contrasts between theatricality and intimacy, and city and country, splendidly on "Sapokanikan," named for the Native American settlement located where Greenwich Village stands.

As she layers the ghosts and memories of old Dutch masters, potter's fields, Tammany Hall, and allusions to Percy Bysshe Shelley's Ozymandias, the music nods to ragtime and other vintage American styles; it could be overwhelming if she didn't return to the simple, poignant refrain: "Do you love me? Will you remember?" Indeed, despite its literacy and embellishments, Newsom's music is never just an academic exercise.

The album's emotional power grows as it unfolds: "Divers" itself reaches deep, bringing the album's longing to the surface.

"A Pin-Light Bent" finds Newsom accepting that time is indeed finite with a quiet, riveting intensity, building to the majestic finale "Time, As a Symptom," where the personal, historical, and cosmic experiences of time she's pondered seem to unite as she realizes, "Time is just a symptom of love." Newsom can make her audience work almost as hard as she does, but the rewards are worth it: Dazzling, profound, and affecting, Divers' explorations of time only grow richer the more time listeners spend with them.