On March 6, 1963, the John Coltrane Quartet played a session at the famed Van Gelder Studios in Englewood Cliffs, New Jersey. They recorded for approximately five hours—they had a show at Birdland in midtown Manhattan to get to later that evening. The tape was never released and was thought to be lost after Coltrane’s record label, Impulse!, was bought by ABC Records, and the archives were purged. But a mono copy tape that Coltrane took home from the session recently resurfaced, and the results are being touted as a lost Coltrane album.

It’s unknowable if Coltrane, who died in 1967, ever really intended for the session captured on Both Directions at Once—which comes out Friday, June 29 on Universal under the resurrected Impulse! imprint—to become an actual, finished album. My gut thinks not, otherwise he and his producer, Bob Thiele, would have gotten Impulse! to release it. The session is roughly contemporaneous with a pair of essential efforts, 1963’s Impressions and 1964’s Live at Birdland, and was recorded at the time Coltrane was shedding his rapid-fire be-bop “sheets of sound” in favor of the free-jazz-informed mysticism that defined his final years. As his son Ravi Coltrane says in the liner notes, “To my ears, it was a kicking-the-tires kind of session.” In just a few short months, the ever-forward-looking Coltrane was on to the seismic artistic developments that would lead to his 1965 masterpiece A Love Supreme, and this session was already ancient history.

Which is not to say there isn’t a wealth of astonishing music on Both Directions at Once. This is the legendary Coltrane “classic” quartet—with Elvin Jones on drums, Jimmy Garrison on bass, and McCoy Tyner on piano—performing at the peak of its powers. The music is knotty, agile, and dances like mercury, and Coltrane is tirelessly excavating new sounds on his saxophone. It’s challenging, physical music, constantly adventurous and flowing with curiosity and momentum. Sweet melodic phrases transform into sulfurous, fanged interjections, and then back again, often within the same measure.

The two untitled, previously unheard works are among the main draws, and a third, given the title of “Slow Blues,” might just be the album’s best track. But even the compositions Coltrane eventually released as different recordings—including “Impressions” and his rendition of the Nat King Cole song “Nature Boy”—sound markedly different in these incarnations. A second disc with alternate takes of some of the songs is included in the deluxe version, including multiple renditions and refinements of “Impressions.”

All of which suggests that with this recording, Coltrane was searching, asking questions, reaching out into the dark without the pressure of coming up with something presentable. And to me, that’s even more exciting than a so-called “lost” Coltrane Quartet album. Instead, we get to peek behind the curtain at a very productive session—there’s close to 90 minutes of music here, from a single afternoon’s effort—and listen to masters hard at work. It’s a genuine thrill. recommended