I joked to an older friend that the crowd gathered to see the reunited Gang of Four at the Showbox on Friday, May 6, was the same as had attended the Slint reunion two months prior, plus some old people. But the Slint crowd was almost monastic in its fervor. They regarded the band in a weirdly religious way, as bedroom prophets whom most of the attendees had never gotten the chance to see the first time. It was obviously the first time for most of the Go4 crowd, too, but if like Slint they’re less famous as a band than as an influence (see whatever “punk-funk” band is on the cover of The Fader this month), Gang of Four were always furiously rhythmic, whatever their clenched-teeth rigor. I haven’t seen that many 40-somethings move that much in one place this side of a salsa lesson.

For a while, I’d planned to write this review in the voice of someone who’d only heard 1991’s Mall and 1995’s Shrinkwrapped, the albums that vocalist Jon King and guitarist Andy Gill released under the full band name. In fact, King, Gill, Portland-resident bassist Dave Allen, and drummer Hugo Burnham did play a Shrinkwrapped number: “I Parade Myself,” whose title says it all. Nevertheless, they stuck mostly to the just-reissued, still blistering 1979 debut, Entertainment!, 1981’s Solid Gold, and the EPs and singles from the same period. Which meant they were, yep, an oldies act, however resonant those oldies might still be and however sharp King in particular looked. King is the first over-40 rock musician I’ve seen with a mostly unbuttoned shirt that I didn’t instinctively wish would cover it up, already. He, Gill, and Allen moved constantly, switching microphones like a tri-screen trading projected images, smacking down the mike stands so often that the stagehands were nearly as visible as the performers. Which didn’t exempt them from shtick, particularly when King beat a microwave with a club (amplified and delayed, for percussion) like it was the patriarchy itself.

All that fell away with the set’s final song, 1981’s “To Hell With Poverty”; as they performed it, everyone in the room held their breath. It belongs to the handful of greatest single-song live performances I’ve ever seen. When they came back, they did a good version of “We Live as We Dream, Alone,” and then “Damaged Goods,” the best song on Entertainment! Improbably, it was as good as “Poverty,” and considerably more tense: The band rumbled into the Gill-sung bridge for a few bars before he opened his mouth, and the crowd filled it in: “Damaged goods/Take them back,” four times, before Gill began. Shocked, my friends and I stood gape-mouthed before the Gang appeared one final time. The song: “I Found That Essence Rare.” You don’t say, fellows.