PROVIDENCE — Jackson Browne worked hard last night at the Providence Performing Arts Center. And as if the usual workload of a three-hour show wasn’t enough, he gave himself the added burden of working without a set list, playing what popped into his head, and occasionally taking requests from the audience, sometimes even if it was for a song he didn’t remember all that well. What that resulted in was a romp through his back catalogue of the type that most artists say they “wish” they could do but in recent years only Elton John has done.

Strolling onstage without an introduction and heading straight into “The Barricades of Heaven,” “Sky Blue and Black” and “Birds of St. Mark’s,” Browne paused amid the 15 acoustic guitars and the electric piano lined up on the stage to consider doing something “a little more introductory.” No dice — “I’m Alive.”

Browne joked, “I’m struggling with the self-knowledge that I’m lazy enough to just stand up here and do whatever you tell me to do.” And while he didn’t quite do that, and occasionally joked that a shouted request was the best way to get him not to do a particular song, on his own volition he took on tunes that were a challenge — “I’m the Cat” (despite slipping up on a lyric), “She’s Got to Be Somebody’s Baby” and “Here Come Those Tears Again,” both of which he explained he wasn’t quite sure how to play the piano parts on, and a song from his forthcoming album (coming out in fall) for which he said it was physically impossible to recreate the recorded structure. This is not what most pop stars do, especially ones who have been around this long, and the sense that you were watching a real work in progress outweighed the occasional sameness of the songs (about which he also joked).

Like in a Greek tragedy, where all the battles and beheadings happen offstage, the most distinctive feature of the music of Jackson Browne is that it comes from the times in between. It’s about reflection, about consideration. It’s post-breakup, post-reconciliation, sometimes both, almost always post-something.

That means most of his stuff, including what he played last night, lacks a certain rock ‘n’ roll attitude. (There were exceptions last night, including the sprightly, boastful “I’m the Cat,” the political “Looking East” and the driving “Nothing But Time,” with guitar tech Manny Alvarez on electric guitar.) But what it gains is the sense that the time and place of the music is here and now.

You could see it last night — there was no awkward shedding and donning of dramatis personae from one song to another. It’s music written by a guy at a piano or behind a guitar, and it loses very little in the translation to the stage, either musically or thematically. (The slide guitar-driven “Your Bright Baby Blues” missed a full-band accompaniment, though.) It’s hard to believe he’s waited this long in his career to put out some solo acoustic albums and do a tour like this.

Of course, even at a show like this, you’ve got to end with the hits, and they came thick and fast at the end — “The Pretender,” a mashup of “Our Lady of the Well” and “Take It Easy,” then encores of “Runnin’ On Empty” (which worked surprisingly well in the acoustic context) and “I Am a Patriot.”

rmassimo@projo.com