On Feb. 18-21, the Seattle Symphony Orchestra, under the baton of a fellow Pulitzer Prize-winning composer, Marvin Hamlisch, will honor Broadway legend Stephen Sondheim as part of its Pops series.

Hailed by The New York Times as “the greatest and perhaps best-known artist in the American musical theater,” composer-lyricist Stephen Sondheim will celebrate his 80th birthday next month. No one can say Seattle has ignored that fact.

A few months ago, Sondheim appeared at Benaroya Hall for an onstage conversation about his career with New York Times columnist and former theater critic Frank Rich.

Sondheim told some entertaining showbiz stories, but he also discussed his early lessons in writing musicals and described his legacy as divided between two eras working with different directors: Harold Prince (“Company”) and James Lapine (“Sunday In the Park with George”).

Sondheim was introduced that night by Seattle Men’s Chorus artistic director Dennis Coleman, currently preparing the SMC for “Glitter and Be Gay,” a tribute to Sondheim and Leonard Bernstein in June.

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On Thursday, the Seattle Symphony Orchestra, under the baton of a fellow Pulitzer Prize-winning composer, Marvin Hamlisch, will honor the Broadway legend as part of its Pops series.

Hamlisch, principal Pops conductor of the Seattle Symphony, Colorado Symphony and orchestras in San Diego, Washington, Milwaukee and Pittsburgh, has, like Sondheim, garnered a number of prizes beyond the Pulitzer. (In Hamlisch’s case, a Tony, Oscars, Grammys, Emmys and Golden Globes.)

Despite that parallel and the fact they work in the same business, Hamlisch says his decision to fete Sondheim was not born out of friendship.

“We don’t have a big relationship,” says Hamlisch by phone from New York. “It’s very cordial, and he will work with me on the Washington version of this show (i.e., with the National Symphony Orchestra). No doubt I know more lyricists than he does. Sondheim doesn’t need any; he’s the complete package.

“It made a lot of sense to do a tribute now,” Hamlisch says. “He’ll be 80 soon, and there are lots of plans to celebrate him in London and the Kennedy Center (in Washington in the spring). I didn’t want to wait until his 90th birthday. I might not be around.”

From the wealth of possible material for the Seattle program, Hamlisch says he looked at each show and took the best songs that worked outside their original context, including a suite from “Sweeney Todd,” “Not a Day Goes By” (from “Merrily We Roll Along”), “I’m Still Here” and “Broadway Baby” (both from “Follies”), and “Send In the Clowns” (from “A Little Night Music”).

Hamlisch admits to a particular attachment to “Company’s” beautiful song about opening up to love, “Being Alive.”

“In time, lyricists become our philosophers,” Hamlisch says. “That line in the song that goes, ‘Alone is alone, not alive.’ That’s my mantra.”

Five seasoned vocalists will join Hamlisch and the orchestra on stage, including Broadway veterans Liz Callaway (“Merrily We Roll Along”), Patti Cohenour (from the original company of “Phantom of the Opera”), Carol Swarbrick (“Side by Side by Sondheim”), Allen Fitzpatrick (“The Sweet Smell of Success”) and Seattle’s Brandon O’Neill (“Wonderful Town”).

Hamlisch says the world of musical theater is different now from its glory days.

“Composers used to write a show a year,” Hamlisch says, “so there were many more great songs and hits. Now, a show is strapped to its book, to what it’s about. The book has become more important than the songs. It’s a rough time for composers and lyricists.”

Tom Keogh: tomwkeogh@yahoo.com