I once made a pact with myself that I wasn't going to buy any new records until I figured out the ones I had. That was until I realized the thing I liked about Charlie Parker or Laurie Anderson was that at some pure deep level, their music couldn't be figured out. There isn't some all-purpose passkey that unlocks their meaning.

The song around which I formed my eternal-mystery theory was not some illegible bebop map or a question mark from "Big Science." The song that hammered home the notion that listening to good music was like watching a quiz show without cue cards was from a genre not known for its elliptical subtleties -- Dixieland. Specifically, it was Louis Armstrong doing that old dirge, "St. James Infirmary." When I was 14, I listened to the one Armstrong record I had every night before I went to sleep -- theoretically to help my own trumpet playing (which is what I told my sister across the hall when she'd had quite enough), but really because I was hooked on getting spooked. "St. James Infirmary" never stopped scaring me, never opened up -- and thus never closed down.

Every time the song came on, I closed my eyes and went to the movies. It's that cinematic, the minor key working as a kind of lighting, midnight blue gels on a few random spots. You hear the smudged brass of Armstrong's trumpet before you hear his voice, harking back to the sad joy of a New Orleans funeral parade. The camera comes in for a close-up as the band slides into a smooth shuffle and Armstrong starts to sing: "I went down to St. James Infirmary/Saw my baby there/She was stretched out on a long, white table/So sweet, so cold, so fair." It's a stark yet moving image, a thrilling twofer, the way the sentimental action takes place in a place as clinical as a hospital morgue.

Armstrong's timbre as both a trumpeter and a vocalist is the perfect match for such a mood, a perfect American marriage of the gruff and the tender -- which is one reason the song's next turn is such a surprise. "She can look this wide world over/But she'll never find a sweet man like me." She's dead, right? She won't be looking. This doesn't make any sense unless you take into account the selfish way the living regard the dead. Mourning is often pure solipsism -- what am I going to do? But the narrator of this song is curiously so stuck up that he feels sorry for his loved one, not because she won't be doing any more breathing, but because she just lost the grace of his presence. It's so petty. And so human.

The next verse omits the dead girl altogether. Now he's imagining his own death, and it couldn't get more selfish. When he sees himself as a corpse, it's as an ad for his own success. He doesn't think about the people or places he'll miss. He wants to be buried in a Stetson hat. "Pin a $20 gold piece on my watch chain," he commands the air, "So the boys will know I died standing fat."

This song gave me the shivers then and it gives me the shivers now. Not just because it's a morgue scene, not just because of the cold body lying there on a table instead of a bed, but because of the chill of the man's words. Hearing it as a young girl, hearing it before I ever fell in love myself, it frightened me because of the way it shoots down the idea of love as a true possibility. If you need love in part to know you'll be missed when you're gone, what does it mean if your sweetheart stands over your icy corpse and -- instead of wishing to rejoin you on some astral plane -- fantasizes about impressing his buddies with a big dumb coin?

That's an ugly thought. But the song's so pretty. The bad thought is expressed in good poetry -- cool phrases such as "sweet man like me," "Stetson hat," "$20 gold piece" -- phrased by a captivating voice working through an addictive blues melody and orchestrated to clarinet and piano perfection. The reason I could listen to the song over and over and never quite figure it out, never get bored -- and the reason the song has been covered by so many performers -- lies in its utter ambiguity. Which is to say, in its freedom. The fact that the song doesn't entirely make sense is an invitation for everyone from Cab Calloway to a new trip-hop band called Snakefarm to get in there and do a little detective work. That jump-cut from the morgue's cold white table to the man's cold dark heart demands interpretation.

Anna Domino, the Snakefarm chanteuse, makes "St. James Infirmary" and other hoary old laments like "Tom Dooley" and "House of the Rising Sun" sound positively glamorous on the album "Songs From My Funeral." Domino recently told hearsay magazine, "These songs remain relevant, moving, and scary. To keep them from becoming relics they get reinterpreted every few decades."

That depends on your definition of the word "relic." A relic in the medieval Christian sense is a holy object that could be wholly creepy. Talismans of mystery and desire, relics were frequently hacked-off body parts of saints. "Let's walk 200 miles to kiss the tooth of John the Baptist!" said the medieval pilgrim.

In a secular world, songs like "St. James Infirmary" work the same way. That's what a cover version is -- a pilgrimage, a chance to traipse to the song and fill in the blanks. The riotous Cab Calloway soups it up and turns the wake into a party, clanging swinging horns around the room as if to raise the dead. Eric Burdon and the Animals rewrite the song so they can stop off at a bar before the viewing since, sensibly, they need a drink first. And Lily Tomlin, inexplicably, once did the song on "Saturday Night Live." Vaguely pissed off and a little too who-gives-a-shit for my taste, her performance nonetheless captures the song's essential weirdness. Because: a) Why did she choose this particular song for this particular show in the first place? b) Who's idea was it to dress up the SNL band, a bunch of guys with random facial hair, as nurses? And c) Isn't it a little too cute that before she can start singing the song, she has to take a thermometer out of her mouth? (That's a prop joke we would have been above even in the 4-H talent show.) So even though her actual performance is a little lackluster, to see Tomlin with a flower behind her ear sitting on top of Nurse Paul Schaeffer's grand piano is nonetheless mesmerizing.

My favorite version of the song, even more than Armstrong's, is by Bobby "Blue" Bland. On his album "Two Steps From the Blues," he skips the Stetson hat/watch chain nonsense and actually performs it as a true love song, adding the unselfish thought that he wishes he could take her place and that "she was all I ever lived for." Snakefarm call their album "Songs From My Funeral," but Bland's version is the only one that's actually respectful enough to be played at a funeral. Bland has the same blueprint as Armstrong, and even has a brass band backing him up, but with the way his voice throbs and tears up and practically collapses, he convinces the dumbstruck listener that if the short song were any longer it would kill him dead.

The fact that "St. James Infirmary" can go from Bobby Bland's suicide to Cab Calloway's dance party, Eric Burdon's bar and Lily Tomlin's brain is an indicator of the song as a kind of blank screen, a place to project oneself onto. Or maybe it's a black hole: The origins of "St. James Infirmary" are characteristically mysterious. Sometimes, one imagines because of specific lyrics or arrangements, it is attributed to Duke Ellington associate Irving Mills, sometimes to a Joe Primrose (or Joe Primerose) -- Armstrong's various recordings of the song divide between these two. Usually it is credited as "traditional." I buy the latter. Even if it was authored in the last 100 years by an identifiable songwriter, the fact that nearly every singer of the song changes its words around suggests that it holds the malleability of an ancient folk song. That word infirmary has the British air of those old Scotch-Irish ballads (my researches found a St. James Infirmary in Dublin as far back as 1667), and you can see how a jazz hipster of the 1920s could make the dead girl his "baby" in a New York minute, even if she'd been a "lady" since Elizabeth was queen.

But I like to think "St. James Infirmary" predates the Tudors. It is called "St. James," isn't it? The shrine of St. James at Spain's Santiago de Compostela was the focal point of the medieval pilgrimages. It was at the end of the pilgrimage route, the place where all the crazy zealots eventually ended up. As Dante Alighieri wrote at the end of the 13th century, a pilgrim can be defined "in the narrow sense" as "the man who travels to or from the sanctuary of St. James." For medieval Christian pilgrims, going down to St. James was a grueling, once-in-a-lifetime blowout. Thanks to records, the modern music pilgrim can crawl under the covers and go down there every night. The only tough question is who you're going with -- Bobby or Louis? Snakefarm or Cab?