For decades, the Beach Boys’ SMiLE — the pop magnum opus that Brian Wilson wrote and recorded from summer 1966 through spring 1967, before he was forced to abandon it — was the most mythical lost album in rock history. Resurrected, completed, and finally released in 2004, it was, for some of us, the holy fulfillment of our Brian-Wilson-is-God dreams. (I think it’s an even greater record than Pet Sounds.) The revelation of The Smile Sessions ($165, out Nov. 1), a nearly seven-hour compilation of the original recordings, is that the album, though unfinished — it needed sequencing and a lot of vocal tracks — was basically all there. Yet in this gorgeous deconstructed form, you can hear how it came to be regarded as the sound of Brian Wilson coming apart. He bends harmonies around corners they’d never been in pop before, and he makes the harpsichord as vital as the guitar. The five CDs are like a documentary of Wilson in the studio, orchestrating the album like a fusion of Phil Spector, Stanley Kubrick (”This’ll be take 25”), and Johann Sebastian Bach. But since the sublime totality of it existed only in his head, listening to Sessions is a bit like looking at the Sistine Chapel ceiling — in a hundred separate pieces.