When Son House returned to performing in the 1960s, he played “Death Letter” so often it became his signature tune. It was a highlight of every setlist, and sometimes he’d run through it multiple times during a show, as though something within the song eluded him. He sang it like he had to puzzle something out or find some dark secret at the song’s core, which made every performance sound slightly different. He would invert the guitar riff, reorder the verses, change the lyrics, borrow from different sources, vary the tempo: sometimes fast and jumpy, sometimes slow and languorous. The most popular version, which he recorded in the 1960s, is a fast version, with a nervy twitch in his guitar playing and an emotional urgency in his singing.

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Compare that to the new version of “Death Letter”, which appears on Forever On My Mind, an album of lost recordings assembled and produced by Dan Auerbach. House recorded it in an intimate setting, with his manager Dick Waterman running the tape and with no plans for commercial release. He slows the song down and stretches it out. “Well, I got a letter this morning/How do you reckon it read?” he asks the listener, and you know exactly how it read, even if you’ve never heard the song before. You know someone he loves is dead and gone. House lingers in the moments: reading that letter, seeing the body at the morgue, watching the casket lowered into the ground, facing a lonely future until their reunion on Judgement Day. Perhaps it’s a different person on the cooling board, who demands a different rhythm of grieving.

While the popular version is urgent and anguished, this newly unearthed “Death Letter” is understated, subdued, but haunting in its own way as House contemplates the unfathomable finality of death: life stops for one person, but sorrow continues for those left behind. It’s as moving a performance as House ever set to tape. Forever On My Mind catches the artist at the peak of his abilities, delivering eight songs – including one, the title track, that he never recorded elsewhere – that showcase his emotive vocals and his dexterous and emphatic bottleneck style of guitar playing. Most of all it highlights his ability to inhabit a song fully, whether it’s humorous (a profane “Preachin’ Blues”) or grave (a devastating “Levee Camp Moan”) or tender (“The Way Mother Did”). Because he never played anything the same way twice, this sounds like an album of all-new material, one that adds a revealing chapter to his eventful life.

House is a crucial figure in rural acoustic blues, a student of Blind Lemon Jefferson, who passed those lessons down to Robert Johnson and Muddy Waters. Oddly enough, his original calling was the Gospels. Born in 1902 deep in the Mississippi Delta, but raised further south in New Orleans, House was more interested in the Church than the juke joint – although not by much. He started preaching when he was 15, but his drinking and carousing eventually drove him from that profession. The experience probably inspired “Preachin’ Blues”, an old song he dusted off for Forever On My Mind. Singing from experience, House deadpans every punchline: “I wanna be a Baptist preacher, so I don’t have to work,” he explains, equating the clergy with snake oil salesmen. But he finds himself too worldly, too profane, too drunk to command a congregation. All that hollerin’ and Bible-thumpin’ proves more taxing than expected, and it’s not long before he’s putting that church behind him.

When House left that calling, he became fascinated with blues music, especially the slide guitar players he saw in Mississippi, and he quickly developed his own style, mixing slurred, staggering bottleneck riffs with frantic picking. He shows that off throughout Forever On My Mind, especially on “Empire State Express”, where he mimics the rhythms and momentum of a runaway train; the song moves so relentlessly that it sounds like he’s shovelling coal into an engine, not strumming a guitar. He combined that approach with an ecstatic vocal delivery that he’d honed at the pulpit. His secular career was briefly sidelined in the late 1920s, when a man fired a gun at him on stage. House fired back and killed his attacker, earning him a 15-year prison sentence at Parchman Farm (where Bukka White and many other bluesmen did time). House served only two years.

After his release, House recorded nine sides for Paramount Records, eight of which were released commercially and zero of which sold well enough to warrant further sessions. He didn’t record again for another decade, until Alan Lomax came through Mississippi and taped him playing with a small band. In 1943 he retired from music altogether and settled down in Rochester, New York, where one of the greatest guitar players in America worked as a railroad porter and chef. When Dick Waterman finally tracked him down in the early 1960s, House didn’t even own a guitar, nor did he have any idea that his small catalogue of recordings had been discovered by a new generation of musicians, almost all of them white and many of them British. Even though it meant having to relearn old songs he’d long forgotten, he jumped at the opportunity to resurrect his music career. House spent the rest of the 1960s and the first half of the 1970s releasing old and new music and playing coffeehouses, college campuses and folk festivals around the world.

Like many “rediscovered” bluesmen of his generation, House found Dick Waterman to be a tireless manager who recorded his clients frequently – to help them relearn old material but also to preserve their repertoire as part of the historical record. House emerges from these recordings with what sounds like a new energy, especially on “Louise McGhee” and “Pony Blues”, but he also displays a new authority, as though his decades away from the music world gave him a different perspective. Age might have worn away at his voice, but it remains agile and expressive, nimbly navigating the tricky rhythms of “Empire State Express” and conveying a profound gentleness on “The Way Mother Did”. He sings the latter in heartbreaking past tense, as though she’s long gone, but the memory of her affection remains comforting.

What threads these eight songs together into a true album rather than just a compilation is the idea – the threat, the inevitability – of leaving and being left. Partly that’s due to Auerbach’s judicious curation, but that fear of loss animates almost all of Son House’s music, if not all of the blues in general. That comes through most prominently on the title track, which opens with a stuttering guitar theme and a wave of low moans, as he ruminates on a lost lover. Perhaps it’s the same woman from “Death Letter”. “I gets up in the morning at the break of day/I be just hugging the pillow, honey/Where you used to lay,” he sings, and no other couplet on Forever On My Mind quite captures the reality of absence so beautifully. House conveys as much joy on these songs as he does pain, telling us so many years after his death that we cannot experience one without the other.