A few years ago, we tried to come up with a list of the best Motown songs of all time. We set out to pick just 80 minutes' worth -- one CD -- but eventually backed down and settled for twice that. There was simply too much great music coming off that record label in the late '60s and early '70s to trim the list to 80 minutes.

Over time, we've had second thoughts about some of the songs that we put on the list, and some that we left out. But we've never wavered in our assessment of the best single that Motown ever released: "Ain't No Mountain High Enough," by Marvin Gaye and Tammi Terrell. And that's got to put that record on a list of the best sound recordings ever made.

It's two and a half minutes of pure joy. The Motown house band, a.k.a. the Funk Brothers, work some of their finest magic, turning what might be a cloying ballad into something that makes the listener want to dance with abandon. The rhythm section -- probably Pistol Allen Uriel Jones on drums and James Jamerson on bass -- is at the heart of things, and although there are violins in the studio, it's quite clear who's boss.

The first two verses and choruses are nice enough, but it's in the bridge that the track really takes off. It's two bridges, really -- the first one along the lines of what went before, but then a few bars of a key-change hook that builds up to the last verse. And when the song gets back to that familiar ground, everything is floating along in an irresistible groove that could seemingly go on for hours.

It's over way too soon, but that's part of the beauty of it. There isn't a wasted half-second in the whole thing.

The singers of the duet were one familiar name (Gaye) and somebody whom most Motown fans had never heard of before (Terrell). Gaye had done duets with women previously -- Mary Wells, Kim Weston, and Oma Page -- but Terrell was new to the Motown roster. They recorded the song separately -- Terrell first, then Gaye. The tape of Terrell's recording session reveals that Motown had another male voice guiding her along, although he wasn't supposed to, and didn't, do much with it. It was probably one of the producers, Harvey Fuqua or Johnny Bristol. His voice was filtered out, and Gaye took Terrell's track and surrounded it with his own soulful delivery.

Fuqua and Bristol had been totally psyched about the project. Legend has it that when Motown boss Berry Gordy showed them "Ain't No Mountain High Enough," the two of them jumped up and down. They knew just from the material that they had a big hit in the making. Little did they know that it would be the first in a string.

The song had been written by a couple named Nickolas Ashford and Valerie Simpson. These two were both songwriting partners and life partners, and they had already had success with a pair of songs that Ray Charles had turned into hits: "Let's Go Get Stoned" and "I Don't Need No Doctor." Motown picked them up after it parted ways with some other writers in a royalty dispute. Simpson wrote the music, and Ashford the words.

If you take apart the lyrics to "Ain't No Mountain High Enough," you won't find a money quote in there. The language is all pretty prosaic. The rhymes are clever, to be sure, but there's no turn of phrase that will bowl anybody over. That makes the strength and durability of the lyrics a bit surprising. It may be that they are so obviously heartfelt, but perhaps it's just that they fit the music, and the singers, so well. They're part of a much larger synergy. It's the same way with all the Gaye-Terrell-Ashford-Simpson hits. You can find poetry like that on Hallmark greeting cards, or late-stage Hall & Oates albums, and it's not worth 99 cents. But over Simpson's music, it's exquisite.

Ashford & Simpson and Gaye & Terrell were the perfect combination, and after "Ain't No Mountain High Enough" there were a series of hits, whose names are familiar to Motown fans. But a brain tumor struck down Terrell, and her death at age 24 wiped out disrupted Gaye's career for years. He was never the same, and he too would meet a tragic, premature demise.

Ashford and Simpson went off to pursue other ventures. Diana Ross covered "Ain't No Mountain High Enough," and they wrote a couple of other hits for her. Chaka Khan started her solo career off right with their "I'm Every Woman," the lyrics of which were apparently a bit of a challenge for Ashford, who wasn't any woman, much less every.

But the couple had always wanted to be performers, despite Motown's lack of interest. Eventually they got their wish, and after they were married and became parents, they embarked on a successful career as singers together. Their biggest success was "Solid," a track that made a big splash in the heyday of MTV music videos in 1984. They didn't perform much after the '80s, but they kept writing songs. They bought a bar in Simpson's hometown of New York City and presented musicians there, both well known and aspiring. They cut an album with Maya Angelou in the '90s. And they were supportive of younger folks coming up in the music business:

Mr. [Jermaine] Paul recalled Mr. Ashford telling him to carry a tape recorder to capture musical thoughts before they disappeared.

"He said, 'Press record,' " Mr. Paul recalled. "Always press record if you walk in and you are humming something. That’s coming from somewhere. Those are the things that are given to you."