Randy Newman has reached an age (he’ll be 65 next month) and stature (Oscar, Grammys, Emmys, boxed set) at which some have begun to suggest that he has transcended the role of acerbic entertainer to become a classic American wit and social critic. The Los Angeles Times, for example, has likened him to Mark Twain. Good call — listening to Newman’s song “Sail Away” takes way less time than reading Huckleberry Finn and says almost as much about where we come from. Of course, Twain churned out prose at a breathless pace, whereas the Newman faithful have endured waits of nearly a decade apiece for his last two studio albums. Which makes the recent return of the bruising ironist and mimic of ugly voices, on the sharp new Harps and Angels (as opposed to the huggy paterfamilias of “I Love to See You Smile”), all the more welcome. And Newman the touring performer? Forget about it — the man hasn’t played here in a generation. Whether you approach it as history lesson, cultural indictment or just plain pop, his solo show at the Folly is one of the year’s essential shows.