SOMERVILLE -- ''Here is a song of teenage angst and brandy-induced, suicidal stupidity," a grinning Stephen Stills told an audience that had sold out the Somerville Theatre Tuesday evening. ''I saved myself hundreds of thousands of dollars in therapy."
The tune, ''4+20," was from Crosby, Stills, Nash & Young's 1970 album, ''Deja Vu." Most telling about the moment was that, despite the romantic fatalism of the song's message, its now 61-year-old author was still around to sing it to packed houses.
As the bluesy core of one of the most celebrated, if volatile, harmony groups in pop history, as well as a member of the short-lived country rock forbears Buffalo Springfield, Stills has a considerable amount of history under his belt -- or rather, his untucked silk print shirts (selling for $100 each in the lobby). And although his warm but worn voice wasn't always up to the task Tuesday night -- those multipart CSN&Y harmonies were missed on chestnuts such as ''Helplessly Hoping" and ''Southern Cross" -- the guy who fancied himself a grizzled soul man in his 20s has finally lived long and fully enough to realize those youthful grasps at wisdom.
Splitting his 90-minute set roughly in two parts (half solo acoustic, half electric with full band), Stills ran through both his back pages and newly written chapters with equal aplomb. The ancient ode to subterfuge, ''Treetop Flyer," cruising on Stills's crafty finger-picked acoustic guitar and crusty outlaw vocal, retained the mischievous glee of a covert reconnaissance mission.
Likewise, the new ''Ole Man Trouble" (one of half a dozen selections performed from his latest album, ''Man Alive!"), was a husky highlight that found Stills seated behind a piano delivering one of his strongest vocals with a gospel flavor reminiscent of Ray Charles. Still others bespoke the politics of the Woodstock era, during which he came of age. (Yes, Stills and his sturdy yet workmanlike band weighed in with a gritty reading of ''Woodstock," Joni Mitchell's three-minute time capsule).
A stirring version of the anti-war meditation ''Daylight Again" was preceded by pointed criticisms of the Bush administration's interpretation of liberty, as was a slow, menacing take on his trenchant Buffalo Springfield-era anthem, ''For What It's Worth" (Stills introduced it as ''an old song that still carries entirely too much meaning"), which prompted the night's first sing-along.
Stills seemed most at home, and most invigorated, when peeling off blistering, bluesy solos on electric guitar, as he did on the muscular ''Wounded World" and the soaring ''Dark Star." The new, calypso-flavored plea to ''Feed the People" made for a better sentiment than song, but Stills's heart was in the right place. Which is more than one can say for some people.