Al Green doesn’t tour very often, he’s only released four albums in the last 17 years, and the last one was four years ago.

But when the president of the United States sings a line from one of your songs at a fundraiser—and it’s all over the cable news channels and the Internet the next day—well, that’s when you know you’ve still got it, that your legacy holds a prominent place in popular culture.

Most readers will recall the wall-to-wall coverage of that moment, on January 19, when Barack Obama stepped up to the podium at a fundraiser at New York’s Apollo Theater and delivered an impromptu and impressively soulful rendition of the first line of Green’s “Let’s Stay Together,” after Green had performed there earlier in the evening.

“I heard about it the next morning, when someone called me to tell me that sales of the song went up overnight,” Green told the Wall Street Journal. “His voice sounded great. I was going to ask if he could sing another bar or two—but he is the commander in chief, so you don’t want to lean too hard.”

It’s easy to understand why Green could still capture the imagination of the leader of the free world: Green is one of the Top 3 or 4 soul singers of the last half-century, and possesses one of the smoothest, most seductive voices in the history of soul music—or maybe even in the entirety of popular music.

And his romantic hits of the 1970s—“Let’s Stay Together,” “Tired of Being Alone,” “I’m Still In Love With You,” etc.—were so swoon-inducing that Jon Stewart once jokingly asked Green how many babies he thought had been conceived while Green’s songs were being played as “mood music.”

Green wasn't just naturally blessed with a sensual, supple voice, though. He’s also an artist—a singer who learned to use unique phrasing, falsetto swoops and little sighs and cries to heighten the emotion or seductiveness of the song.

Green, who comes to Hill Auditorium on Saturday for an Ann Arbor Summer Festival show, was born in Arkansas, but moved to Grand Rapids with his family in 1955, when he was 9 years old. It was in Grand Rapids that Green got the music bug, and formed his first group, as a teenager.

And it wasn’t Green’s glorious pipes alone that turned his ‘70s tracks into such timeless soul-music classics. He also had a secret weapon—Willie Mitchell, Green’s producer and arranger. After they met, the two quickly became simpatico, with Mitchell first prodding Green to sing with more subtlety and nuance than he’d been using before they met.

"Willie taught me to sing like Al Green, who had been too busy trying to sound like everyone else,” Green told the Journal.

Mitchell’s meticulously crafted productions and arrangements included languid but accented grooves, swirling organ flourishes and taut, punchy horns.. The result was something of a hybrid between the gritty Memphis soul of the Stax stable—Sam & Dave, Otis Redding, Booker T & the MGs, etc.—and the more lush Philly-soul sound.

The grooves were also unique in that Mitchell got the drummer to play an accented 3/4 groove, on the cymbals or high-hat, within the song’s 4/4 rhythm.

Most Green fans know the story about how, in 1974, when he was at the top of his game, musically, his troubled ex-girlfriend poured a pot of boiling grits on him, scalding him, before committing suicide. Two years later—partly due to that harrowing experience, says Green—he had a spiritual experience, became an ordained minister and bought a church in Memphis.

He recorded a few R&B records after that, but when he fell off a stage and narrowly avoided serious injury in 1979, he took that as a sign from God that he should retire from making secular records, and he spent most of the ‘80s recording gospel albums.

In 1992, he returned to making R&B records, with “Don’t Look Back”—a UK-only release. He’s made four R&B albums since then, the most recent being “Lay it Down” (2008), which was produced by Ahmir “?uestlove” Thompson from the Roots and keyboardist James Poyser, who’d worked with many popular R&B / hip-hop acts, like Erykah Badu and Common.

The album featured guest turns by such R&B notables as John Legend, Corrine Bailey Rae and the Dap-King Horns. While Thompson and Poyser wanted to reach out to younger audiences, they also clearly had a great reverence for Green’s legacy—because much of the record evokes the sound and vibe of those great Mitchell-produced discs of the ‘70s.

And Green is presently working on a new album. “I have seven songs done, and three more to go!,” he said in an interview with the Washington Times.

Green’s return to R&B—both in the studio and onstage—has caused him to experience some internal conflicts.

For starters, he doesn’t care much for touring, because he doesn’t like being away from his church for very long. "There's so much happening on the spiritual side of my life now, which is why we're trying to limit the number of dates I'm playing," he told the Journal.

"I'm between a rock and a hard place. The rock is the R&B and the hard place is my tabernacle. My love has switched from the carnal to something more eternal and everlasting……"I often struggle with the spiritual man and natural man—the two roles God gave me. Where is the dividing line? It's hard."

Kevin Ransom is a freelance writer who covers music for AnnArbor.com. He can be reached at KevinRansom10@aol.com.