I've visited Graceland twice and on both occasions what affected me were the homely details. The 70s toaster and microwave in the tiny kitchen. Elvis's private jet, the Lisa Marie, named after his daughter, parked near the house; at the back of the plane a double bed in which Elvis slept, presumably in a narcotised fug.
Ted Harrison, in his thorough examination of Elvis's cultural afterlife - The Death and Resurrection of Elvis Presley - points out that the Presley family might never have had to open their home to the public if the King hadn't died in what was, by rock'n'roll standards, penury. He was down to his last million, largely through the avarice of Colonel Tom Parker, his long-time manager.
As soon as he heard of his sole client's sudden death, Parker signed a hasty contract with Vernon Presley, Elvis's rather hopeless father, boasting: "I owned 50 per cent of Elvis while he was alive, and I own 50 per cent of him now he's dead."
A few years after Elvis's death, he had bled the estate dry.
Priscilla, Elvis's ex-wife, rode to the rescue, with what Harrison calls her "untutored flair" and "innate toughness". Graceland was opened to the public (the ground floor, not the upstairs where he had died in the bathroom). She seized control of Elvis's image and reined in the flourishing trade in Love Me Tender Dog Chunks and Elvis Sweat ("Elvis poured out his soul to you, so let his perspiration be your inspiration"). Images of Elvis that were disrespectful or showed him as overweight were banned.
But the Presley family no longer owns Elvis. In 2013, Authentic Brands Group, a business that markets images, took over from Elvis Presley Enterprises. Harrison argues Elvis is "rising Phoenix-like from the flames of the old family business, fanned and fuelled by international capitalism". Is Elvis safe in their hands, or will the bottom line be their only concern?
One of the ideas in Harrison's new book is that "maybe, as Christianity declines, an improbable Elvis faith will fill some of the vacuum".
He points, as evidence, to the words of a fan's offering at the graveside, which implicitly equates Elvis with Jesus and Graceland's meditation garden with the Garden of Gethsemane.
He talks to a psychiatrist claiming to have found "hundreds" of people who believe they communicate with Elvis psychically. He looks at shrines and Elvis churches, such as the Presleytarian Church in Australia, with its tenets ("Don't Be Cruel"; "Don't Be a Hound Dog").
Harrison's book invites comparison with Greil Marcus's brilliant Dead Elvis: Chronicle of a Cultural Obsession (1991). Marcus caught the spirit of Elvis better than anyone. The point, he wrote, is that Elvis is not comprehensible; certainly not with the standard reductive blather about how he blended white country and black blues.
"You can listen to every proto-rockabilly singer ... and what you hear in Elvis simply isn't there. You can listen to Elvis at the very beginning and it is there; you just can't tell what it is."
• In 2014, there were worrying rumours that Elvis's two planes were to be moved away from Graceland to make room for shops or hotels. Fans protested and the aircraft are still there. But perhaps soon you'll be able to invite a virtual Elvis to your party. Scientists may one day make a bodysuit with emotion-stimulating sensors so that his fans can "feel Elvis caressing and kissing them".
• August 16 next year will be the 40th anniversary of his death: in Memphis, they expect record numbers for the traditional candlelit procession of Elvis Week. In a big year, 70,000 visitors flock to Graceland's meditation garden, where he is buried. There is a fountain, an eternal flame and a statue of Jesus with his arms outstretched.