When you arrive in your thirties and see a few of your heroes die, you realize there's something to be said for eating right and getting some sleep. The devil doesn't visit your shoulder quite as often. You still long for mad kings or a big night out, but you want a bit more substance, a sense of the wry and the rueful, an awareness that after Saturday night comes Sunday morning. In short, you want the Mekons to amble onstage like a cadre of political agitators after another wine-drenched "theory" session, spouting wisecracks and self-mockery ("Fear us, pity us, we are the Mekons"), clutching beers, quite amused to have found themselves with an audience, and lurch into the first song of a set that will last all night and leave you weary, laughing, and believing that one day the brilliant will rule and the idiots will learn.

The Mekons are an "English Punk Band" that has existed in various forms since 1977. They're now based in Chicago, and are not really a punk band anymore, except in politics and attitude. They make brilliant, funny, raucous, epic rock and roll music. They are what the Clash could have been by now if they hadn't made it big. A lot gets made of their changes in personnel, but the line-up has been essentially stable for over 15 years--singer/guitarist Tom Greenhalgh, singer Sally Timms, singer/guitarist Jon Langford, accordionist Rico Bell, bassist Sarah Corina, drummer Steve Goulding, occasionally fiddler Susie Honeyman. In that time they have produced a handful of the best albums you ever heard, and a handful more that are almost that good, all the while laboring under indifferent record labels and meager sales. (Their very best record, "The Mekons Rock'n'Roll," their only on a major label, is currently and criminally out of print.) They are more than a band, they are an art collective: In addition to releasing 11 albums and touring almost constantly since 1984 (when they re-formed for benefit shows in support of a Welsh miners' strike), they've staged art-gallery shows of painting, photography, and film, and produced a loosely conceptual book-CD set called "United," which contains those elements as well as excerpts from Living in Sin, the Mekons' novel in progress. All songs, all paintings, all writings are credited "Mekons." There are also equally viable side bands: Sally Timms has recorded two beautiful solo records, and the Waco Brothers, "Chicago's #1 Wasted Swing Band," have recorded three.

In short, the Mekons are many things in addition to being the greatest rock and roll band in the world. Because people like me write insistent pieces like this, they exist almost on the level of myth--but I've seen them three times in the past two years, a testament to their visibility and commitment as a working band. Live, the Mekons are so loose they seem effortless. They are capable of turning the stage into a rollicking party down at the pub, fulfilling all those projected rock'n'roll fantasies of freedom, excess, hilarity, and compelling socialist commentary on the plight of the worker in an exploitative sociopolitical system whose only rewards are material. They may be sarcastic, but they brook no irony. They might make like cynical old drunks, but the Mekons care, and it seems as though all of Western history is compressed into their songs. They're at their best when they fall into a churning, mid-tempo groove, the guitars grind out anthemic lead lines, the accordion swells, and the singers' voices crash together with another treatise on tangled lies and exploitation. They're equally affecting when Sally is given the spotlight, gently swaying to a drifting Western theme, coolly cataloging a host of sins like a post-modern Julie Andrews. Steve is their secret weapon, subtle, steady, and powerful, while Sarah sticks to her business, smiling in the background like a shy younger sister. Jon is probably the musical leader on rhythm and lead guitar, driving the songs and soloing with fiery intensity, with occasional help from a smirking Tom. But the Mekons are a five-ring circus with no one wearing the top hat.

So on March 9 at the Bowery Ballroom, I was surprised to find myself drunker than they were. It was like drinking with friends and realizing they're not on the pace, and in fact are looking at you because you're talking much too loud. It was instead a civilized weeknight gig, appropriate to the mood of their new album, "Journey to the End of the Night," a gentle, simply recorded collection, and further tempered by the illness of Sally, who had to leave the stage three times to throw up. She wasn't drunk, she insisted: "I'd be honest if I were." Jon scoffed that she should be like the rest of them: "We throw up onstage . . . and sing into the toilet!"

The set started slowly with a pair of the new songs before arriving at the high leg-kicks of "I've Been to Heaven and Back," the title track of the first volume of "Hen's Teeth and other fragments of unpopular culture," a two-CD retrospective that came out last year. The evening continued like that, striking a balance between the new and the old-new, ruminative English folk songs and lilting reggae, punctuated by tracks from deeper in the catalog, including their loping cover of Hank Williams's "Lost Highway," Mitch-the-dreadlocked-roadie's lead vocal on "Where Were You?", the all-male football-club chorale of "Powers & Horror," and Jon's crib-note version of "The Ballad of Sally," which Sally was too sick to sing herself. Sally did keep coming back, though; when she left the stage for the last time, after dueting with Tom on the bloody lover's lament "When Darkness Falls," Jon said, "Farewell, Queen Sally--we shall not see her like again." The band carried on to finish the set, leaving and being dragged back three times, even after the house lights came on, until Jon begged off, pleading, "We really haven't got any more songs!"

So, it wasn't a night to set the town alight--no falling about the stage, no flying beer. They were a bit more thoughtful, reflective. You often have to put up with some inscrutable bit of experimentation from the Mekons--their career has taught them to serve themselves, not the audience, so you take the bad with the good. It might be reasonable to assume they're on the downside of their career--or at the very least contemplating fewer van trips around the country--and it's equally reasonable to grant them their respite, for it's a good fight they've fought. There's a set list from 1993 pictured in the liner notes of volume two of "Hen's Teeth"; looking at it, I felt real pain and regret that they came nowhere near where I lived in those years. They do not play many of those songs these days. But they'll still lean into "Memphis, Egypt" towards the end of the night, and the exuberance is contagious. The cursed Mekons are truly the last gang in town. The devil will tap your shoulder again some night, and you'll be back.