After flubbing some words to her biggest hit, a 1971 cover of the Band's "The Night They Drove Old Dixie Down," Joan Baez wondered if she was getting enough gingko extract to keep her brain young.

But the years haven't damaged the voice or relevance of Baez, who appeared with a backing duo at the sold-out Birchmere on Wednesday. And while she's doling out homeopathic advice, fans would rather hear what sort of extracts keep Baez, 64, so cool and beautiful.

It helps, of course, that the times really haven't a-changed things too much. As she must, Baez did several tunes she got from her old muse-with-benefits, Bob Dylan. He's never gone away, but the recent Martin Scorcese documentary and our country's recent foreign and domestic foibles have made Dylan's old material, so much of which is joined to Baez's hip, seem contemporary. During an otherwise reverent version of "It's All Over Now, Baby Blue," she mocked Dylan's voice for a verse. "With God on Our Side," a onetime Dylan and Baez duet that chronicles America's history of aggressive behavior, begged for an update. "A Hard Rain's a-Gonna Fall," a song from the last time our country was as afraid of being attacked as it is now, was sad only for its relevance.

Baez also sang "Scarlet Tide," a dose of lefty idealism from Elvis Costello and T-Bone Burnett, a pal from the mid-1970s barnstorming Rolling Thunder tour backing Dylan. And more of the same from Steve Earle: "Jerusalem" and "Christmas in Washington," the latter of which begs for the return of Martin Luther King Jr., Woody Guthrie and Gandhi.

Given her life story, Baez doesn't need somebody else's lyrics to drop names. She told many tales about Being There for moments everybody in the crowd wished they'd been there for. Before an a cappella version of "Swing Low Sweet Chariot," she recalled singing that same tune to wake a sleeping King while both were in Mississippi to march. She remembered getting "The Long Black Veil" from Johnny Cash when he was "cuter than hell." She spoke of going to Crawford, Tex., over the summer and learning that Cindy Sheehan, the face of the newest antiwar movement, has a favorite Joan Baez song: the labor anthem "Joe Hill."

Near the end of her two-hour set, Baez gave her fans the song they wanted most, "Diamonds and Rust." The autobiographical tune tells of her inability to get over a former blue-eyed lover from the Midwest who was good with words and insults ("My poetry was lousy, you said"). She never gives the fellow's name.

The years have been good to Joan Baez, shown here at September's concert at the Washington Monument.